Oh dear, I seem to have fallen at the last.
I have a full grid plus the quote and its author, but can't quite work out the last bit.
The only answer that seems remotely thematic is 9a, but I can't see anything or anyone related to the theme that surrounds it.
I can see the singular of 9a in roughly the centre of the grid at a sloped angle, with the middle letter Y at the bottom of 5d but, again, can't see a name around it?