Thanks malone, MPR, and candledave, much appreciated. Everything makes sense,
except I'm still confused about the bit from 31ac. That was exactly the clue I thought must be the one in question, based on the process of elimination, but the wordplay already works well for me as is:
"Start" (exclamation), striking/removing Henry/H, plus "over" as in "regarding" — to me this adds up to what I gather the definition to be.
I assume the first word is the one being modified, but I don't see how or why. Something around star/orb, maybe? I do apologise for my denseness here!