Not evil maybe; just lacking restraint (7)
I believe the answer is:
violent
'lacking restraint' is the definition.
'not evil maybe' is the wordplay.
'maybe' indicates anagramming the letters.
'not'+'evil'='notevil'
'notevil' anagrammed gives 'VIOLENT'.
'just' is the link.
I am not very happy about this link. It may be part of another bit of the clue.
(Other definitions for violent that I've seen before include "not peaceful either" , "Intensely forceful" , "Brutal - intense" , "Immoderate" , "Bloodthirsty" .)