Data Backup. The word "DATA" can be found spelled backwards in each of the theme answers.
17-Across. Topper for a toreador: MATADOR HAT. Not sure how long the hat stays on in the ring, however,
30-Across. How sale items are priced: AT A DISCOUNT.
And the Unifier:
63-Across. System administrator's task ... and a hint to what can be found in 17-, 30- and 47-Across: DATA BACKUP.
Across:
17-Across. Topper for a toreador: MATADOR HAT. Not sure how long the hat stays on in the ring, however,
30-Across. How sale items are priced: AT A DISCOUNT.
47-Across. "I'm so disappointed!": WHAT A DOWNER.
And the Unifier:
63-Across. System administrator's task ... and a hint to what can be found in 17-, 30- and 47-Across: DATA BACKUP.
Across:
1. Remove politely, as a hat: DOFF. This is becoming a crossword staple.
5. Muscle cramp: SPASM. // And 22-Down: Idiocyncratic twitch: TIC.
10. Hang onto: HOLD.
14. Assert as true: AVER. A crossword staple.
15. One with dreads: RASTA.
16. Out of the wind: ALEE.
19. On cloud __: NINE.
20. Fill with joy: ELATE. Fun to have this clue and answer immediately follow the sense of being On Cloud Nine.
21. Feature that results in extra legroom on a plane: EXIT DOOR. Pre-Covid, these seats were hard to get. Extra legroom is a necessity if one is tall. I am short and find the regular seats too small.
23. On __: sans contract: SPEC.
26. Bro's sib: SIS. As in Brother and Sister.
27. Indy 500 letters: STP.
36. Brewed beverage: TEA.
37. Pseudonymous punk rock surname: RAMONE. The name of the band was inspired by the fact that Paul McCarthy would often use the pseudonym "Paul Ramon" when he traveled. The original 4 members of the Ramones have all died: Joey Ramone (né Jeffrey Ross Hyman; May 19, 1951 ~ Apr. 15, 2001) died of lymphoma; Dee Dee Ramone (né Douglas Glenn Colvin; Sept. 18, 1951 ~ June 5, 2002) died of a drug overdose; Johnny Ramone (né John William Cummings; Oct. 8, 1948 ~ Sept. 15, 2004) died of prostate cancer; and Tommy Ramone (né Tamás Erdélyi; Jan. 29, 1949 ~ July 11, 2014) died of cancer.
38. "This isn't looking good": UH, OH!
39. Turn back to zero: RESET.
41. Picnic pest: ANT.
42. Step between landings: STAIR.
43. "__ girl!": ATTA.
44. Stir up: AROUSE.
46. Press into service: USE.
49. Corrosive solution: LYE.
50. PBS "Science Kid": SID. I am not familiar with Sid the Science Kid.
51. Crossed (out): EX'ED.
53. Previews that sound like they belong after the film: TRAILERS.
58. Eye-popping colors: NEONS.
62. Little Boy Blue's instrument: HORN. A reference to the nursery rhyme:
Little Boy Blue come blow your horn,
The sheep’s in the meadow the cow’s in the corn.
But where’s the boy who looks after the sheep?
He’s under a haystack fast asleep.
Will you wake him? No, not I – for if I do, he’s sure to cry.
66. "In memoriam" piece: OBIT. As in the Obituary.
67. Speak from a platform: ORATE.
68. River of Pisa: ARNO.
69. Change the decor of: REDO.
70. Gall: NERVE.
71. Like the 10th frame in bowling: LAST. Hi, Boomer!
Down:
1. Title for Maggie Smith: DAME. Dame Margaret Natalie Smith (b. Dec. 28, 1934) is such a good actress.
2. Speed-skating rink shape: OVAL.
3. Greek cheese: FETA. Feta cheese is a brined curd white cheese made in Greece from sheep milk or from a mixture of sheep and goat milk. It is a crumbly aged cheese, commonly produced in blocks, and has a slightly grainy texture in comparison to other cheeses.
4. Houses with Greek letters: FRATS.
5. Full house letters: SRO. As in Standing Room Only. Probably not permitted by the Fire Marshal in most venues.
6. It may be two on a minigolf hole: PAR.
7. US Open stadium namesake: ASHE. Arthur Ashe (July 10, 1943 ~ Feb. 6, 1993) makes frequent guest appearances in the crossword puzzles.
8. Pringles rival: STAX. Both are some sort of weird potato chips.
9. French painter Henri: MATISSE. Henri Matisse (né Henri Émile Benoît Matisse; Dec. 31, 1869 ~ Nov. 3, 1954) was a French post-impressionist painter.
10. Distributes: HANDS OUT.
11. Hodgepodge: OLIO. A crossword staple.
12. Carson's successor: LENO. Jay Leno (né James Douglas Muir Leno; b. Apr. 28, 1950) replaced Johnny Carson (né John William Carson; Oct. 23, 1925 ~ Jan. 23, 2005) on The Tonight Show.
13. Bambi and Ena: DEER. Disney characters.
18. Leave: DEPART.
24. Greek vowel: ETA.
25. Sporty Chevy: CAMARO.
28. Canines, e.g.: TEETH.
29. Ziti or rigatoni: PASTA. Everything you wanted to know about the Difference between Ziti and Rigatoni, but were afraid to ask.
31. Brief beginning-of-class activity: DO NOW.
32. On key: IN TUNE.
33. DIY mover: U-HAUL. I have used U-Haul a time or two for some moves. The company is currently based in Phoenix, Arizona. The company was started in 1945 by Leonard Shoen (Feb. 29, 1916 ~ Oct. 4, 1999) in Washington State.
34. Loud: NOISY.
35. Stooge count: THREE. Hi, Chairman Moe! Welcome to the world of blogging.
40. Erodes, as savings: EATS INTO.
42. Sister of Venus: SERENA. Venus (née Venue Ebony Starr Williams; b. June 17, 1980) and Serena (née Serena Jameka Williams; b. Sept. 26, 1981) Williams are both tennis stars.
44. Enlarged the house: ADDED ON.
45. Census checkbox: SEX. The Census it taken every 10 years, and this was year.
48. Feel sick: AIL.
52. Window sticker: DECAL.
53. Thunder god: THOR.
54. Courtroom garb: ROBE.
55. Desertlike: ARID.
56. Uncommon: RARE.
57. Betelgeuse is one: STAR. The name Betelgeuse is believed to be a French corruption of the Arabic word for the bright star found in the constellation of Orion.
59. Gumbo ingredient: OKRA. We had Okra last week.
60. Sisters: NUNS. Hi, Lucina!
61. Lady Macbeth's "damned" tormenter: SPOT.
64. Off-road transp.: ATV. As in All-Terrain Vehicle.