Decadent English party receives fine (6)
I believe the answer is:
effete
'decadent' is the definition.
(synonyms)
'english party receives fine' is the wordplay.
'english' becomes 'e' (abbreviation).
'party' becomes 'fete' (I've seen this before).
'receives' means one lot of letters goes inside another (inserted letters are received).
'fine' becomes 'f' (abbreviation).
'fete' placed around 'f' is 'ffete'.
'e'+'ffete'='EFFETE'
(Other definitions for effete that I've seen before include "Weak, effeminate" , "Over-refined; weak" , "Lacking in power" , "Over-refined, pretentious" , "Weak, decadent" .)