Business associate upheld hire charge (7)
I believe the answer is:
partner
'business associate' is the definition.
(business partner)
'upheld hire charge' is the wordplay.
'upheld' is a reversal indicator.
'hire' becomes 'rent' (synonyms).
'charge' becomes 'rap' (both can mean blame or responsibility).
'rent'+'rap'='rentrap'
'rentrap' backwards is 'PARTNER'.
(Other definitions for partner that I've seen before include "Either one of a couple" , "Mate or collaborator" , "Spouse or business collaborator" , "Husband or wife" , "One sharing home or business" .)