Using no force is perfect for criminal (7)
I believe the answer is:
lawless
'for criminal' is the definition.
(I've seen this before)
'using no force is perfect' is the wordplay.
I cannot quite understand how this works, but
'force' could be 'law' (law is a kind of force) and 'law' is found in the answer.
The remaining letters 'less' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for lawless that I've seen before include "Anarchic, without any controls" , "Anarchy" , "Ungoverned" , "disobedient" , "Slew Sal for being criminal" .)