No Ifs, Ands, or Butts? The last word of each theme answer refers to one's tushie.
17-Across. * Youthful blush, say: ROSY CHEEKS.
26-Across. * Idler at the shore: BEACH BUM.
53-Across. * Parlor piece: LOVE SEAT.
62-Across. * Frank holders: HOTDOG BUNS.
And the unifier:
37-Across. Hit from behind ... and what the answers to starred clues are?: REAR ENDED. A bit of a racy theme, don't you think?
Across:
1. Urges to attack, with "on": SICs.
5. Actor Hawke: ETHAN. Ethan Hawke (b. Nov. 6, 1970) has appeared on the Big Screen, television and live theater. His first wife was Uma Thurman (b. Apr. 29, 1970).
10. Chew (on): GNAW.
14. Help out during exercises, as in a gym: SPOT.
15. LP player: PHONO.
16. One of a model's repertoire: POSE. Before he was an actor, Ted Danson (b. Dec. 29, 1947) was a model.
19. Common country suffix: -STAN. Think of Afghanistan; Turkmenistan; Uzbeckistan; Tajikistan; Pakistan ...
20. Palindromic magazine: ELLE. This magazine is often found in the crossword puzzles.
21. __ Alamos, NM: LOS. Los Alamos is best know for being the home of the atomic bomb.
23. Oil field?: ART. Cute clue.
24. Look up to: ESTEEM.
28. Double-crosser: RAT.
29. Lavish bash: FÊTE.
31. Spanish rice dish: PAELLA. Yummers! I had some fantastic paella when I was in Barcelona. I have never tried to make it, but here is a recipe.
32. Not commissioned, after "on": SPEC.
34. Author Jaffe: RONA. Rona Jaffe (June 12, 1931 ~ Dec. 30, 2005), was a prolific author. I read a lot of her work when I was in college.
36. Like Lady Liberty's crown: RAYED.
40. Farrier: SHOER. Technically, although not just any shoer. A farrier is essentially a podiatrist for a horse and does more than just shoe horses.
43. Quite a distance: AFAR.
44. Cocksure: SMUG.
48. Coming from the heart?: AORTAL.
50. "Your guess __ good ... ": IS AS.
52. Solver's cry: AHA!
55. Docking places: WHARFS.
57. Cold War mil. program: SDI. As in the Strategic Defense Initiative, also known as the Star Wars Program.
58. Gate announcement, briefly: ETD. Think of the gate at the airport. Estimated Time of Departure.
59. Modern mining target: DATA.
60. Cantina cooker: OLLA.
67. Causing yawns, often: DULL.
68. Archer's weapon: ARROW.
69. Mine entrance: ADIT. This word is derived from the Latin aditus, which means entrance.
70. Central Iowa city: AMES. Ames, Iowa is the home of Iowa State University.
71. Watch partner: LEARN.
72. Peter or Paul (but not Mary): TSAR. Peter I, Tsar of Russia (June 9, 1672 ~ Feb. 8, 1725) was known as Peter the Great. Paul I, Tsar of Russia was the son of Catherine the Great. He was not so great and was later murdered.
Down:
1. Cold War state: Abbr.: SSR. As in the Soviet Socialist Republics.
2. Wall St. news: IPO. As in Initial Public Offering.
3. "Les Misérables" girl: COSETTE. There are so many versions of this Victor Hugo classic.
4. Bob or weave: STYLE. As in a hair style.
5. Collectibles like ticket stubs and matchbooks: EPHEMERA. These are things that are enjoyed for a short period of time. Actually, if they are collectibles, don't they last and last? The ticket may be used for a short period of time, but you can keep the stub forever.
6. Not just any: THE. Meh!
7. Gardening tool: HOE.
8. Bracelet site for one on house arrest: ANKLE.
9. "Outta luck!": NO SOAP! The phrase "No Soap!" apparently first appeared in publication in a nonsense poem in 1755. You can read the poem here.
10. Docs who don't specialize: GPs. As in General Practitioners.
11. Especially: NOTABLY.
12. Usually: AS A RULE.
13. Lost it: WENT MAD.
18. Musical pitch indicator: CLEF.
Treble, Bass, Alto, and Tenor Clefs
22. Close call: SCARE.
24. Trauma ctrs.: ERs. As in Emergency Rooms.
25. Maple extract: SAP.
26. Perk from work: BENEFIT.
27. Two of them are better than one: HEADS.
30. When tripled, a 1970 WWII film: TORA.
33. Minotaur's island: CRETE.
35. Santa __: dry winds: ANAs.
38. Clear the board: ERASE.
39. Deplete, as a bank account: DRAW DOWN.
40. Grill-cleaning solution: SAL SODA. I had never heard of Sal Soda. Apparently it is a sodium salt of carbonic acid.
41. Gangster: HOODLUM.
42. One of the Wright brothers: ORVILLE. Wilbur (Apr. 16, 1867 ~ May 30, 1912) and Orville (Aug. 19, 1871 ~ Jan. 30, 1948) Wright were aviation pioneers. Because Wilbur died many years before his brother, Orville, Orville may have revised history to give himself a greater role in flight than his brother.
45. Plunders: MARAUDS.
46. Old TV dial letters: UHF. As in Ultra High Frequency.
47. Really good time: GAS.
49. Deadly: LETHAL.
51. Heavy carpet: SHAG. Also a hair style.
54. Put on a pedestal: ADORE.
56. Facing the pitcher: AT BAT.
61. "Happy Days" diner: AL'S.
63. __-la-la: TRA.
64. Palme __: Cannes award: D'OR. The Palme d'Or (French for Golden Palm) is the highest prize awarded at the Cannes Films Festival.
65. Actress Long: NIA.
Nia Talita Long (b. Oct. 30, 1970)
66. Philharmonic sect.: STR. As in Strings.
Here's the Grid: