Second person in court ain't put away for providing cannabis (6)
I believe the answer is:
spliff
'for providing cannabis' is the definition.
'second person in court ain't put away' is the wordplay.
'second' becomes 's' (common abbreviation).
'person in court' becomes 'plaintiff'.
'put away' indicates named letters should be taken away.
'plaintiff' with 'aint' taken away is 'pliff'.
's'+'pliff'='SPLIFF'
(Other definitions for spliff that I've seen before include "Cannabis cigarette" , "Cannabis joint" , "Dodgy smoke" , "Marijuana cigarette" , "Joint (for smoking)" .)