Three got drunk simultaneously (8)
I believe the answer is:
together
'simultaneously' is the definition.
(thesaurus)
'three got drunk' is the wordplay.
'drunk' indicates an anagram.
'three'+'got'='threegot'
'threegot' is an anagram of 'TOGETHER'.
(Other definitions for together that I've seen before include "self-confidence" , "stable" , "United; touching" , "tied" , "at the same time" .)