For the auditor, check rule (5)
I believe the answer is:
reign
'rule' is the definition.
(synonyms)
'for the auditor check' is the wordplay.
'for the auditor' shows a homophone (sound like).
'check' becomes 'rein' (both can mean to control or limit).
'rein' is a homophone of 'REIGN'.
(Other definitions for reign that I've seen before include "Period during which someone is dominant" , "Have sovereign power" , "Sovereignty" , "Rule over in Niger" , "Sit on a throne" .)