Queue to leave when stuck in bumptious social gathering? (8,5)
I believe the answer is:
cocktail party
'social gathering?' is the definition.
(cocktail party is a kind of social gathering)
'queue to leave when stuck in bumptious' is the wordplay.
'queue' becomes 'tail' (I've seen this before).
'to leave' becomes 'part' (parting means leaving or separating).
'when stuck in' is an insertion indicator.
'bumptious' becomes 'cocky' (I've seen this before).
'tail'+'part'='tailpart'
'tailpart' inserted inside 'cocky' is 'COCKTAIL PARTY'.
(Another definition for cocktail party that I've seen is " Function with drinks".)