Thanks, Malone. I may well have gone wrong on the third element. There is an obvious (human) “S-word” with a similar letter count to my third highlight but my grid-staring didn’t reveal it (which may well be a failure on my part, of course).
A possibly mis-spent part of my life means that I always see the “S-word” with the initials CHI in front. (Not an abbreviation fou d in the BRB, I think.) So I am probably predisposed to be pedantic about it,
All of which is entirely beside the point. I enjoyed the puzzle. So job well done.