Arbiter has item to repair (5)
I believe the answer is:
refit
'to repair' is the definition.
(I've seen this before)
'arbiter has item' is the wordplay.
'arbiter' becomes 'ref' (I've seen this in other clues).
'has' says to put letters next to each other.
'item' becomes 'it' (I've seen this in other clues).
'ref'+'it'='REFIT'
(Other definitions for refit that I've seen before include "Overhaul (ship)" , "Replace or repair equipment as part of a general overhaul" , "Equip for further use" , "provision of new equipment" , "Mend" .)