Broken fence or implement (7)
I believe the answer is:
enforce
'implement' is the definition.
(I know that implement can be written as enforce)
'broken fence or' is the wordplay.
'broken' is an anagram indicator.
'fence'+'or'='fenceor'
'fenceor' is an anagram of 'ENFORCE'.
(Other definitions for enforce that I've seen before include "Compel observation of" , "Ensure observance of rules" , "Compel adherence to (a law)" , "Make (a law) obeyed" , "Compel or impose obedience, say to law" .)