Roam semi-nude somehow causing offence (12)
I believe the answer is:
misdemeanour
'offence' is the definition.
('misdemeanour' can be a synonym of 'offence')
'roam semi-nude somehow' is the wordplay.
'somehow' is an anagram indicator.
'roam'+'semi'+'nude'='roamseminude'
'roamseminude' is an anagram of 'MISDEMEANOUR'.
'causing' acts as a link.
(Other definitions for misdemeanour that I've seen before include "Minor offence" , "Minor wrongdoing" , "Minor violation" .)