Violated a moral law (6)
I believe the answer is:
sinned
'violated a moral law' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for sinned that I've seen before include "Transgressed the moral law" , "Gave moral offence" , "Send in (anag.)" , "Violated a moral law" , "was wicked" .)