Beginners turned on by bad habits (7)
I believe the answer is:
novices
'beginners' is the definition.
('novice' can be a synonym of 'beginner')
'turned on by bad habits' is the wordplay.
'turned' shows that the letters should be reversed in order.
'by' says to put letters next to each other.
'bad habits' becomes 'vices' (I've seen this in another clue).
'on' backwards is 'no'.
'no'+'vices'='NOVICES'
(Other definitions for novices that I've seen before include "starters?" , "church members?" , "Converts" , "Beginners, who have not sinned?" , "Tyros" .)