Broken fences or implements (8)
I believe the answer is:
enforces
'implements' is the definition.
('enforce' can be a synonym of 'implement')
'broken fences or' is the wordplay.
'broken' indicates anagramming the letters.
'fences'+'or'='fencesor'
'fencesor' with letters rearranged gives 'ENFORCES'.
(Other definitions for enforces that I've seen before include "Compels obedience, say law" , "Makes sure a law is observed" .)