Scorn drink after party (2,4)
I believe the answer is:
do down
'scorn' is the definition.
(to do down is to scorn or mock)
'drink after party' is the wordplay.
'drink' becomes 'down' (to down something can mean to drink it quickly).
'after' says to put letters next to each other.
'party' becomes 'do' (do is a kind of party).
'down' put after 'do' is 'DO DOWN'.
(Other definitions for do down that I've seen before include "Cheat" , "Criticise" , "Informally, get the better of or swindle" .)