Begin to break up the party (5)
I believe the answer is:
binge
'party' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'begin to break up' is the wordplay.
'to break up' is an anagram indicator.
'begin' is an anagram of 'BINGE'.
'the' acts as a link.
Can you help me to learn more?
(Other definitions for binge that I've seen before include "Eat greedily" , "Bust" , "Self-indulgent session" , "A drinking bout" , "Overindulge" .)