... pulse is zero after the party (5)
I believe the answer is:
beano
'the party' is the definition.
(I've seen this before)
'pulse is zero after' is the wordplay.
'pulse' becomes 'bean' (I've seen this before).
'is zero' becomes 'o'.
'after' is a charade indicator (letters next to each other).
'bean'+'o'='BEANO'
(Other definitions for beano that I've seen before include "Kids' comic" , "Enjoyable party" , "binge" , "Celebration" , "Rowdy jollification" .)