That's Gotta Hurt

Explanation: If you combine 2 words (hint from the prompt) in 6 of the rows, you get new words that can be the fill for 8 other clues. By combining 6A with 10A you get MODERATE which could be the fill for the 57A clue. 23A and 24A = 4D. 25A and 27A = 60D. 32A and 33A = 59D. 40A and 41A = 22A. 46A and 49A = 21A. 50A and 51A = 18A. 64A and 65A = 56A. The first letters of the uncombined words spell MUSTACHE or MUST ACHE.

Nice work, LarsCaine! We'd still love to see one of your metas on "Smooth Sailing Sundays" someday.

Good one! I like the puzzles where solving comprises a series of revelations