Theme: It ain't over till it's over - The sharing of the same word by the four longest entries.
17A. Began without hesitation: DOVE RIGHT IN
27A. Was heedless behind the wheel: DROVE RECKLESSLY
43A. Mentioned earlier: ABOVE REFERENCED
57A. Unseemly disclosure of personal details ... as seen in 17-, 27- and 43-Across?: OVERSHARING
Argyle here. I'm afraid I tried to overthink this puzzle. Just the word OVER repeated and somewhat placed over each other. If you see more, please share.
Across:
1. Prepare for a bodybuilding competition: OIL UP. If you missed seeing LATS yesterday, I'll give you oiled-up lats today.
6. Online discussion venue: FORUM
11. Freon or neon: GAS
14. Capital of Bangladesh: DHAKA. More.
15. Maureen known as Hollywood's "Queen of Technicolor": O'HARA. Nice Bio.
16. LP's 33 1/3: RPM. or RsPM, if you care.
19. Copy: APE
20. Place for a massage: SPA
21. Texas A&M athlete: AGGIE. Formerly named The Agricultural and Mechanical College of Texas (1871–1963), hence the Aggies.
22. Disney's Little Mermaid: ARIEL
24. Take from the top: REDO
26. Without a musical key: ATONAL
32. Seal-hunting swimmers: ORCAs
33. Actor Ving of "Pulp Fiction": RHAMES. Gangster Marsellus Wallace (Ving Rhames)
34. Scolding sound: {TSK!}
35. Showers or drizzles: RAINS
36. Small amount: DAB
39. Irish playwright Sean: O'CASEY."It's my rule never to lose me temper till it would be detrimental to keep it."
41. Low card: DEUCE and 37D. Card that may be high or low: ACE
47. Unruffled: SERENE
48. Run __: go wild: AMOK
49. Careful types take them: PAINS
50. Bring about: CAUSE
53. Showy accessory: BOA
56. Previous to, to Dickinson: ERE. Emily Dickinson, poet.
60. Inmate: CON
61. Amusement park thrills: RIDES
62. Nick of "Cape Fear": NOLTE. Cape Fear, the psychological thriller film from 1962 was remade in 1991 with Nick Nolte as Sam Bowden, the Gregory Peck role.
63. Explosive letters: TNT
64. Makeup mishap: SMEAR
65. Recital pieces: SOLOs
Down:
1. Gambler's concern: ODDS
2. "Eat up every moment" breakfast chain: IHOP
3. Geological Hawaiian souvenir: LAVA ROCK
+
4. Musical Hawaiian souvenir: UKE
5. Mardi Gras events: PARADES
6. "Around the World ... " hero Phileas: FOGG
7. "Well, howdy": "OH, HI"
8. Mortgage figure: RATE
9. Sch. with a Providence campus: URI. (University of Rhode Island, again) Motto: Think Big. We Do.
10. Sea cow: MANATEE. Marine mammal.
11. Bits of sand: GRAINS. “Like sands through the hourglass...."
12. Losing lawyer's recourse: APPEAL
13. Like Limburger cheese: SMELLY
18. Composer Stravinsky: IGOR, conducting a snippet of "The Firebird".
23. Flag maker Betsy: ROSS
25. A Gabor sister: EVA. Zsa Zsa died Sunday just shy of 100 years old ~ TMZ
26. Gift for the poor: ALMS
27. Web address part: DOT. A tittle, if you will.
28. Cos. with Xings: RRs. Cos. means companies? Wiki says yes.
29. Wipe out: ERASE
30. Tribal leader: CHIEF
31. Rapper West: KANYE. Kanye Omari West
35. Prized by collectors: RARE
36. Platypus feature: DUCKBILL. If you thought the manatee looked odd...
38. Place to retire: BED
39. Baking spot: OVEN
40. Keeps from being blue?: CENSORS. Cute clue.
41. Humbles: DEMEANS
42. Brian of ambient music: ENO
43. Characteristic: ASPECT
44. Affect: BEAR ON
45. Prepare, as new students: ORIENT
46. Like too-quick decisions: RASH
50. Surrender: CEDE
51. Neighborhood: AREA
52. KGB country: USSR
54. Clued in about: ON TO
55. Grows older: AGES
58. Vigor's partner: VIM. Vim and vigor, crudely known as p*ss and vinegar.
59. Outback hopper, for short: ROO. If you watched the video, you know they are related to the platypuses.
Argyle