The top row of blanks may be replaced with a standard five-letter dictionary word such that when placed on the grid, all Down entries still spell valid words. (e.g. if the word started with "A", the new 1D entry would be A***.) All words which fit this criterion are solutions to the meta-puzzle.
If I've missed any alternative solutions, please do mention them! The only other solution I've come across as of now is the abbreviation ASSTS, which doesn't feel right to me.