puzzle

 ACROSS

  1 Word before "Sea" or "snake"

  6 Sounds at pounds

 10 Musician's booking

 13 "Am not" retort

 14 Medicinal succulent

 15 "Duke of ___" ('60s song title that contains two titles)

 16 *"Thrift Shop" rapper (Theme hint: Note the last several <00AD>letters of each starred clue's answer)

 18 Fruit in a gin cocktail

 19 Bang shut

 20 National Gallery of British Art, today

 21 Part of an act

 22 The best man gives one

 24 Soul seller?

 25 *"Cagney & Lacey" co-star

 31 Hiking trails

 35 Clearing in the woods

 36 Three-layered cookie

 37 Order a la ___

 39 Penalize, informally

 40 Bras and slips

 42 Polite chaps

 43 *Former country that residents called Deutsche Demo-kratische Republik

 46 Veer, like a jet

 47 Vice President Harris

 51 Ice's state of matter

 54 Musical about hippies protesting the draft

 56 Show up for

 58 Analogous

 59 *Out too late

 61 Pull with effort

 62 ___ Pet (terra-cotta "companion")

 63 Lead or gold

 64 Corn unit

 65 Lip or cheek

 66 Little brothers, maybe

DOWN

  1 Engine parts

  2 Ph.D. students' exams

  3 Summarize

  4 Words on a volunteer's name tag

  5 Texter's chuckle

  6 Kawasaki rival

  7 Tons

  8 Skin opening

  9 Take notice of

 10 Wind that may blow down a tree

 11 Golf club with grooves

 12 Elation

 15 Cadillac SUV

 17 Engrave

 21 Leo or Libra

 23 Start's start?

 24 Leg joint

 26 Composer Ned

 27 Make a choice

 28 CNN anchor Burnett

 29 No longer in Drafts

 30 Droops

 31 ___ vault (Olympic event)

 32 Opera solo

 33 Two ___ for a twenty

 34 Hampering

 37 Ship's staff

 38 Make public, as grievances

 41 Old oath that anagrams to "aged"

 42 Dodgeball venue

 44 Dogs from Japan

 45 DEA agent

 48 Concur

 49 Garrets' relatives

 50 Vexed constantly

 51 "The Sweetest Taboo" singer

 52 Gumbo vegetable

 53 One may cheat a polygraph test

 54 "That's funny!"

 55 Yard sale stipulation

 57 Birds that fly almost silently

 59 Lenovo laptops, e.g.

 60 Person who's often booed, briefly

solution