Faulty fence — it I'd replaced (9)
I believe the answer is:
deficient
'faulty' is the definition.
(thesaurus)
'fence it i'd replaced' is the wordplay.
'replaced' indicates anagramming the letters.
'fence'+'it'+'id'='fenceitid'
'fenceitid' with letters rearranged gives 'DEFICIENT'.
(Other definitions for deficient that I've seen before include "less than complete" , "Inadequate" , "Lacking" .)