A drop of whisky before a stage show (5)
I believe the answer is:
drama
'a stage show' is the definition.
(I've seen this in another clue)
'a drop of whisky before' is the wordplay.
'drop of whisky' becomes 'dram' (a dram is a small drink of spirits).
'before' means one lot of letters go next to another.
'a' after 'dram' is 'DRAMA'.
(Other definitions for drama that I've seen before include "sensation" , "Play, emotional series of events" , "Hamlet, say" , "Theatrical play" , "theatre studies" .)