Got together and took single drug (9)
I believe the answer is:
methadone
'drug' is the definition.
(methadone is a kind of drug)
'got together and took single' is the wordplay.
'got together' becomes 'met' (meeting is a kind of getting together).
'and' is a charade indicator (letters next to each other).
'took' becomes 'had' ('have' can be a synonym of 'take').
'single' becomes 'one' (I've seen this before).
'met'+'had'+'one'='METHADONE'
(Other definitions for methadone that I've seen before include "Synthetic analgesic" , "Synthetic drug taken to replace heroin" , "Drug used in treating heroin addiction" , "Narcotic analgesic drug" .)