Actually I have one other non-thematic left, 25a, I have ??O.
Sound of contempt from stupid fellow in Tampa, not half.
Best not to get into theme, as it’s only Thursday evening.
Well, lumen, think of what people shout to express contempt or disapproval. If you then say it twice, here in the UK we think of "blunder" but apparently, according to Chambers, that repetitious form in US slang means a "stupid fellow".
Lumen, that one's a common 'sound of contempt' (definitely not a cheer). If the answer was repeated, forming a six letter word, it'd be a 'stupid fellow in Tampa/America..
Thanks Malone, just got that one a few seconds ago, having finally cracked the theme. Not a subject I had any experience of. I’d heard of one, of about ten! But every day is a school day as they say.
Lumen, glad we could help. I say 'we', Will37 answered (just) before me. I had no knowledge whatsoever of the theme, but the internet is a wonderful thing....