Poulenc’s variation - ultimate in exquisite richness (8)
I believe the answer is:
opulence
'richness' is the definition.
(I've seen this before)
'poulenc's variation ultimate in exquisite' is the wordplay.
'variation' indicates an anagram.
'ultimate in' indicates one should take the final letters.
The final letter of 'exquisite' is 'e'.
'poulenc' anagrammed gives 'opulenc'.
'opulenc'+'e'='OPULENCE'
(Other definitions for opulence that I've seen before include "Luxuriousness" , "State of affluence and luxury" , "Open clue? (anag)" , "Profusion, luxury" , "State of affluence or richness" .)