Not against the law (5)
I believe the answer is:
legal
'not against the law' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for legal that I've seen before include "Street - (1978 Dylan album)" , "Relating to jurisprudence" , "It's acceptable" , "within the rules" , "Referring to the law" .)