Fixing fence, mentor finds application (11)
I believe the answer is:
enforcement
'application' is the definition.
(eg the application of rules)
'fixing fence mentor' is the wordplay.
'fixing' is an anagram indicator.
'fence'+'mentor'='fencementor'
'fencementor' is an anagram of 'ENFORCEMENT'.
'finds' is the link.
(Other definitions for enforcement that I've seen before include "Compulsion" , "Act of compelling compliance" .)