With fib, fail to move court officer (7)
I believe the answer is:
bailiff
'court officer' is the definition.
(I've seen this in another clue)
'with fib fail to move' is the wordplay.
'with' means one lot of letters go next to another.
'to move' is an anagram indicator.
'fib' next to 'fail' is 'fibfail'.
'fibfail' with letters rearranged gives 'BAILIFF'.
(Other definitions for bailiff that I've seen before include "Court official" , "Landlord's agent or steward" , "Landowner's agent" , "Possibly menacing landlord's agent" , "Law officer who helps sheriff, say to foreclose" .)