The necessary expression of disgust after party (5)
I believe the answer is:
dough
'the necessary' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'expression of disgust after party' is the wordplay.
'expression of disgust' becomes 'ugh' (I've seen this before).
'after' is a charade indicator (letters next to each other).
'party' becomes 'do' (do is a kind of party).
'ugh' put after 'do' is 'DOUGH'.
Can you help me to learn more?
(Other definitions for dough that I've seen before include "Flour mixture for bread and pastry" , "Lucre" , "Money (sl.)" , "cash" , "Money (slang)" .)