This puzzle was actually designed to have a theme, but no one understood it so I decided to just make the puzzle themeless. If you feel like a wild goose chase (or maybe you happen to recognize the property the two long Acrosses have?), you can try to figure out the ex-theme, but no one who has tried this was successful (that I know of).
Okay, fine, here it is: RESTARTED and STARTLING are "CHOP WORDs": you can continually remove letters and keep getting words. So like RESTARTED to RESTATED to RESTATE to ESTATE to STATE to SATE to SAT to AT to A. You figure out the sequence for STARTLING.
This puzzle was initially published by me on March 26, 2021.