Abiding by the law (5)
I believe the answer is:
licit
'abiding by the law' is the definition.
(within the rules, opposite of illicit)
This is the entire clue.
(Other definitions for licit that I've seen before include "Honest" , "Allowed as by law, not forbidden" , "in order" , "Allowable" , "Lawful, permitted" .)