Love to drink up after work (4)
I believe the answer is:
opus
'work' is the definition.
(an opus is an artistic work)
'love to drink up after' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'to drink' becomes 'sup' (to sup is to drink).
'up' is a reversal indicator (in down clue: letters go upwards).
'after' is a charade indicator (letters next to each other).
'sup' written backwards gives 'pus'.
'o'+'pus'='OPUS'
(Other definitions for opus that I've seen before include "Musical composition in the soup" , "Musical piece" , "Piece of music (with number)" , "Work of 25 perhaps" , "Soup (anag.)" .)