A drink before the play (5)
I believe the answer is:
drama
'the play' is the definition.
('drama' can be a synonym of 'play')
'a drink before' is the wordplay.
'drink' becomes 'dram' (I've seen this before**).
'before' means one lot of letters go next to another.
'a' put after 'dram' is 'DRAMA'.
(Other definitions for drama that I've seen before include "Theatrical work" , "theatre performance" , "Serious play" , "show of histrionics" , "Theatrical piece" .)