17. Expand regs to one's advantage: STRETCH THE RULES.
28. Impulsively get involved: JUMP IN HEADFIRST.
35. With 38-Across, take a dangerous risk: SKATE ON.
38. See 35-Across: THIN ICE.
61. Do the opposite of what those who 17-, 28- or 35-/38-Across do: EXERCISE CAUTION.
Melissa here. Interesting grid, right? Three grid-spanners in a grid with left/right symmetry. Normally if you turn the grid upside-down, the pattern should be the same (180° rotational symmetry). Clever how the first words STRETCH, JUMP, SKATE are all types of EXERCISE, which is the first word of the reveal answer - makes for a tight theme. This appears to be Owen Travis's LA Times debut.
Across:
1. Rural assent: YES'M.
5. Michelle who wrote "Becoming": OBAMA.
10. Rikishi's sport: SUMO. Japanese word rikishi is a term for a professional sumo wrestler.
Rikishi is also the ring name of Solofa Fatu, an American wrestler. Fatu has a twin brother, and he and his twin both have their own twins. What are the chances of that?
14. Beat fast, as a heart: RACE.
15. __ Wiggum, Lisa Simpson classmate: RALPH. From The Simpson's.
16. Bracketology org.: NCAA. Basketball - National Collegiate Athletic Association.
20. SEA postings: ETAS. ETA = Estimated Time of Arrival. SEA is the airport code for Seattle airport. Also referred to as Sea–Tac.
21. Very large: MEGA.
22. Emerald City creator: BAUM. Emerald City is the capital city of the fictional Land of Oz in L. Frank Baum's Oz books, first described in The Wonderful Wizard of Oz (1900).
23. NBC's "Weekend Update" show: SNL. Saturday Night Live.
26. Exile isle: ELBA.
32. Nanny, mostly?: ENS. Three n's in the five-letter word.
33. " ... a farm, __": EIEIO.
34. AP rival: UPI.
41. Carried: TOTED.
42. Sub detector: SONAR. Sub as in submarine.
43. Mystical old letter: RUNE.
46. Salty margarita glass spots: RIMS.
48. Fishy email asking for personal info, perhaps: SPAM. Spam vs. phishing.
51. Many an April birth: ARIES. Zodiac. An Aries is said to be
a passionate, motivated, and confident leader
who builds community with their cheerful disposition and relentless
determination. Uncomplicated and direct in their approach, they often
get frustrated by exhaustive details and unnecessary nuances.
53. Lessen in intensity: EASE.
57. Actress Ullmann: LIV. Norwegian actress and film director.
58. Rights activist Carmichael: STOKELY. Born in Trinidad, civil rights leader, antiwar activist, and Pan-African revolutionary, Stokely Carmichael is best known for popularizing the slogan “Black Power.” He adopted the name Kwame Ture after moving to Africa in 1968.
60. "Planet Money" network: NPR. So much good programming on NPR.
64. Ritzy NYC thoroughfare: PARK AVE. Top Ten Secrets of NYC's Park Avenue.
65. Joins the service: ENLISTS.
66. Taste test request: TRY ONE.
67. Can't bear: DETEST.
Down:
1. Jr. and sr.: YRS. High school or college student years, junior and senior.
2. Chow down: EAT.
3. Lets have it: SCREAMS AT. Ohhhh - sneaky.
4. Connect (with): MEET UP.
5. Hobbit enemies: ORCS. From the book The Hobbit. In Tolkien's works, orcs are a brutish, aggressive, ugly and malevolent race of monsters.
6. Exclamation from Scrooge: BAH. Charles Dickens's miserly protagonist in A Christmas Carol. Ebeneezer Scrooge is "a cold-hearted miser who despises Christmas."
7. Key to some shortcuts?: ALT. Nice clue - computer keyboard. I just got the new iMac - was so pleased that the signature Apple keyboard and magic mouse are now charged wirelessly - no more changing batteries.
8. Meas. with city and highway calculations: MPH. Miles per hour.
9. "If I might interrupt ... ": AHEM.
10. Aptly named baby carrier brand: SNUGLI.
11. Kareem Abdul-Jabbar, in coll.: UCLA BRUIN. Basketball.
12. Sallie __: MAE. Originally the Student Loan Marketing Association. The company's primary business is creating, servicing, and collecting private education loans.
13. Western treaty gp.: OAS. Organization of American States. The OAS has 35 members, which are independent states in the Americas.
18. Suspense novelist Hoag: TAMI.
19. Great Barrier __: REEF.
22. Swindling scheme: BUNKO. I only knew this word from the game (I've never played) - but the spelling for the game is bunco. BUNKO is a
swindle in which a person is cheated at gambling, persuaded to buy a
nonexistent, unsalable, or worthless object, or otherwise victimized.
23. Place for a soccer guard: SHIN. Shin guard.
24. Once known as: NEE.
25. Pain au __: French dessert: LAIT. Translates directly to "milk bread," a humble name for these slightly sweet, elegant, brioche-like rolls.
27. Org. concerned with boxers: ASPCA.
28. Kid: JEST. Verb not noun.
29. Classical prefix: NEO.
30. Exclamation from Homer: DOH. Second clue from The Simpson's.
31. Level: TIER.
36. One of two for 52-Down: TERM.
37. Dot follower, on campuses: EDU. Email address.
39. Doctrine suffix: ISM.
40. Win by a __: NOSE.
44. Locally grown: NATIVE.
45. Like jagged edges: EROSE. Having an irregularly notched or toothed margin as though gnawed.
46. Volleyball star Gabrielle: REECE.
47. Madagascar, e.g.: ISLAND. Second largest island in the world, after Indonesia.
48. Snoozed: SLEPT.
49. "Inside Out" studio: PIXAR.
50. Looney Tunes animator Tex: AVERY. The name is a little obscure, but he created well-known characters such as Looney Tunes stars Bugs Bunny, Daffy Duck, Porky Pig, and Elmer Fudd.
52. Prez before Jack: IKE. Jack = John F. Kennedy. Ike = Dwight D. Eisenhower.
54. Licorice-like flavoring: ANISE.
55. Parking places: SPOTS.
56. Physicist Mach: ERNST. noted for his contributions to physics such as the study of shock waves.
58. Read, as a bar code: SCAN.
59. 'Tis the season: YULE. Linguists debate the origin of the word of
the word Yule. Some suggest the word is derived from “Iul,” the
Anglo-Saxon word for wheel. This makes a connection to a Celtic
calendar, the Wheel of the Year. However, in the Norse culture, “Jul”
refers to the god, Odin. Odin was celebrated during Yule as well.
62. "Citizen Kane" distributor: RKO. RKO Pictures - a subsidiary of Radio-Keith-Orpheum, aka: RKO.
63. Chickadee kin: TIT.