1. Sir's counterpart → MADAM
6. Folded Mexican snack → TACO
10. Young chap → LAD
13. "___ is where a guy gets stabbed in the back, and instead of dying, he sings": Robert Benchley → OPERA
14. Sean of "The Lord of the Rings" → ASTIN
16. Chicken ___ king → ALA
17. Wyoming skiing mecca → JACKSONHOLE
19. Female pig → SOW
20. Gold, in Spanish → ORO
21. Dessert with icing → CAKE
22. Motor City hoopster → PISTON
24. Run out of clothes? → STREAK
26. Like an envelope that's ready to be sent → SEALED
28. ___ Major (constellation) → URSA
30. "Enola Holmes" actress ___ Bobby Brown → MILLIE
32. Bicycle shorts material → LYCRA
35. Computer image → SCAN
37. ID checkers at an airport → TSA
39. Gallery-filled Big Apple neighborhood → SOHO
40. Finger or toe ... or, when read as two words, what you can do to the ends of 17- and 62-Across and 10- and 34-Down → DIGIT
41. "Get outta here!" → SCAT
42. Artificial colorant → DYE
43. Half of a train track → RAIL
44. "That's boring!" → HOHUM
45. Starting point → ORIGIN
48. Grand ___ (achievement in baseball or tennis) → SLAM
50. Hardest to find → RAREST
52. "Let me clarify ..." → IMEANT
56. Gesture suggesting "I see what you did there" → SLYNOD
58. Top poker cards → ACES
60. Monarch at Versailles → ROI
61. Golfer's target ... or prize → CUP
62. End successfully → WORKOUTWELL
65. Comedian Wong → ALI
66. Medieval stringed instruments → LUTES
67. "___, meenie, miney, mo" → EENIE
68. Crunchy sandwich, for short → BLT
69. Camp shelter → TENT
70. Religious ceremonies → RITES