Slip out following a cigarette (6)
I believe the answer is:
spliff
'a cigarette' is the definition.
(I've seen this before)
'slip out following' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'following' becomes 'ff' (abbreviation used in citations).
'slip' anagrammed gives 'spli'.
'spli'+'ff'='SPLIFF'
(Other definitions for spliff that I've seen before include "Cannabis joint" , "Marijuana fag" , "Blow in this tube" , "Marijuana cigarette" , "Cannabis cigarette" .)