What, no axons or D-day today? I feel lost. Untethered. Adrift.
Actually, that's how I felt for much of the puzzle today. I couldn't figure out any of the themed answers, and needed the entire revealer answer less one letter before I could make heads or tails of it. But when I did... Color me impressed.
Things started smoothly enough in the NW, where I filled in the first three down and across answers without any issue. I got into trouble when I guessed TOPknot at 5D: Clip art? (TOPIARY). Things weren't much better in the middle N, when I guessed poet for 8D: One going on foot? (SHOE).
After that, I bounced around, getting very little traction in any area. I knew 27A was solar plexus, but couldn't figure out how to fit it in. Anyway, I got WHILEAWAY at 54A: Kill, as time (very nice!), and although the SW corner was confusing due to the nearly ungettable crossing at HOLI (never heard of it) and ILE (possibly because they're much better known as the Marquesas Islands, even though they're in French Polynesia, I worked my way across the bottom.
There's very little to dislike in this grid, IMHO. I'd never heard of 6A: Sigmatism (LISP), so that's a nice word to pick up. EELED is not great, and GIGLI is better forgotten than remembered, I imagine. Although I'm going entirely by reputation, never having seen it.
I think my favorite clue-answer pair is 18A: Cartoon character created by a marine biologist (SPONGEBOB). That's a great piece of trivia. 1A: Lead on (TEMPT) is pretty good too, and I'll give it a B+.
Thumbs up overall.