1. Palm Sunday remnant used on the first Wednesday of Lent → ASH
4. Milky Way maker … or Milky Way object → MARS
8. Cereal option → MUESLI
14. Word with brain … or body? → PEA
15. Company behind National Pancake Day → IHOP
16. "You can't be serious!" → OHCMON
17. La ___, Bolivia → PAZ
18. Practices on the court → SHOOTSSOOPS
20. Hose fillers → LEGS
22. "___-high by the Fourth of July" (corn farmer's adage) → KNEE
23. "Uh-uh" → NOPE
24. Isolated → SILOED
26. Deep cut → GASH
28. November honoree, informally → VET
29. Shows exasperation, in a way → RONESEYES
31. Two-cent pieces? → OPEDS
33. Burden → ONUS
34. Mega Man console, informally → NES
35. Comedian Costello → LOU
36. Pollen producer on a flower → STAMEN
38. Time off, perhaps? → JETLAG
41. Where someone might keep a tab on you? → PUB
42. Make it → TAG
43. Those in charge: Abbr. → LDRS
45. Assail → BESET
48. Bewilder → THROWFOOP
50. One serving a queen, perhaps → ANT
51. Spicy cuisine → THAI
53. Little squirt → SHORTY
54. Certain bra spec → DCUP
56. Sound from Peppa of kids' TV → OINK
58. Part of Q.E.D. → ERAT
59. Props for one's performance → ROFAPPLAUSE
62. Nonhuman source of spam → BOT
64. Like a premium plan for an account user, maybe → ADFREE
65. The Israelites' golden calf, e.g. → IDOL
66. Neckwear that can't be laundered → LEI
67. Annoy → PESTER
68. Takes from → ROBS
69. Subject discussed in — and also hidden in the name of — the 2019 documentary "Third Eye Spies" → ESP