Passing test, ran in to get drunk! (9)
I believe the answer is:
transient
'passing' is the definition.
('transient' can be a synonym of 'passing')
'test ran in to get drunk' is the wordplay.
'to get drunk' indicates an anagram.
'test'+'ran'+'in'='testranin'
'testranin' with letters rearranged gives 'TRANSIENT'.
(Other definitions for transient that I've seen before include "on the move" , "Here today, gone tomorrow" , "Ephemeral" , "Passing, short-lived" , "gone in a trice!" .)