I believe that the puzzle has a slight mistake. The correct answer to 23A should be eight letters rather than seven. But it's pretty clear what is expected.
I wasn't familiar with the quotation, but it does explain (sort of) what's going on.
23 is as in Brewer’s which differs from Wiki! A strange way to use the quote which combined with the generous clueing means I spent almost as long working out the end game as the grid fill. Thanks tnap.
Having finished (and noted the apparent error at 23), I searched Brewer's and found nothing on the theme at all. The quote is in ODQ but it offers a pretty flimsy justification for the jumbling.
With some long jumbled entries, three of which cross 1a, I think the clues needed to be on the easy side.
Fairly straightforward clues - a couple left to parse. But there was an element of "Guess what I'm thinking" about it. Yes, there was the hint, and yes, we were pointed towards the reference. But even then it was a slog actually to find the relevant entry
Not very satisfactory, I thought. It would have been better if the unclued answers had ended up with real words. I think there should be a ban on wordplay that simply indicates a succession of single letters. Like Scorpius I found nothing relevant in my 2012 Brewer's (19th ed) but maybe I need to buy the new one.
Search seems to be playing up as I get no results for “listener” or “tnap” (mobile version). Is it just me?
I agree with others that the link between quotation and thematic treatment is rather tenuous, and there’s an element of GWIT, but I am grateful for any challenging puzzle at the present time. Thanks Tnap.