Church rules soon broken by nipper? Quite the reverse (5,3)
I believe the answer is:
canon law
'church rules' is the definition.
(I've seen this before)
'soon broken by nipper? quite the reverse' is the wordplay.
I cannot really see how this works, but
'soon' could be 'anon' (synonyms) and 'anon' is present in the answer.
'nipper?' could be 'claw' ('claw' can be a synonym of 'nipper') and 'claw' is found within the remaining letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for canon law that I've seen before include "Body of regulations enacted by the Christian Church" , "Ecclesiastical rule" , "Collection of rules governing a Christian church" , "strict rules" , "ecclesiastical set of rules and regulations" .)