Drink one in play (5)
I believe the answer is:
drama
'play' is the definition.
(synonyms)
'drink one' is the wordplay.
'drink' becomes 'dram' (small alcoholic drink).
'one' becomes 'a' (a thing is one thing).
'dram'+'a'='DRAMA'
'in' acts as a link.
(Other definitions for drama that I've seen before include "Plays as branch of literature" , "Theatrical work" , "Play; exciting situation" , "Hamlet, say" , "Theatrical performance" .)