1. Young fellows → LADS
5. Tied up, as hay → BALED
10. Surrounded by → AMID
14. Plant-based spread → OLEO
15. Echo speaker → ALEXA
16. Largest company headquartered in Oregon → NIKE
17. 1967 hit by the Who, per 68-Across → FORMILESICANSEE
20. Words after "happily ever after" → THEEND
21. Bit of ink → TAT
22. Lack of connectivity → GAP
23. Long-haired bovine → YAK
24. Anabolic steroids, e.g., informally → PEDS
27. College football rival of Michigan, for short → OSU
29. 1978 song by Gloria Gaynor, per 68-Across → SURVIVEIWILL
34. Lead-in to pop or lit → BRIT
36. Award with a "Best New American Theater Work" category → OBIE
37. Midmonth time → IDES
38. Linseed oil source → FLAX
39. Shampoo often in a green bottle → PRELL
40. Remain unresolved → PEND
41. Cause for a miner celebration? → LODE
42. Animal in more than 70 Bugs Bunny titles → HARE
43. Hospital count → BEDS
44. 2008 hit by Katy Perry, per 68-Across → AGIRLIKISSED
47. One of a trio encountered by Ricitos de Oro → OSO
48. Egyptian sun deity → ATEN
49. Solid-rock connector → ASA
52. Forehead marker at the start of Lent → ASH
54. Long-running procedural franchise → CSI
57. Removes forcibly → EJECTS
59. 1973 Bob Marley song covered by Eric Clapton, per 68-Across → THESHERIFFISHOT
63. Currency of Yemen → RIAL
64. Language in which "maunga roa" means "long mountain" → MAORI
65. Unimpressive rating → POOR
66. TV's Griffith, Kaufman or Samberg → ANDY
67. "Take this job and shove it!" → IQUIT
68. Wise counselor of sci-fi who might not be great at karaoke? → YODA