Hey thanks! Glad it was indeed solvable - this was one of my more outlandish ideas.
I didn't actually write original clues (I worked within the 'every second word' constraint to make the clues legible), but a post-Endgame version is a good idea, so here y'all go:
- 1A THEUSA Springsteen's birthplace, in a famous song
- 4A HORNED Like some owls, bulls, Satan, or a standard orchestra?
- 5A ARABLE Worth farming
- 6A NASALS The letters 'n', 'm', and 'ŋ'
- 9A OCELOT Relative of the bobcat
- 10A SERENE At peace
- 1D THANOS Disney villain who's a bit snappy? (And whose actions have impacted this grid)
- 2D HORACE Roman poet who wrote 'Satires' and 'Ars Poetica'
- 3D ERASER What a British person calls a rubber (no, not that one, Yanks!)
- 6D UNBALE Unpack, as hay from a bundle
- 7D SELLON Turn a profit by vending again
- 8D ADESTE First word in the Latin version of the carol 'O Come All Ye Faithful'