Auditor's game (8)
I believe the answer is:
checkers
'auditor's game' is the definition.
'checkers' can be an answer for 'game' (checkers is a kind of game). I am not certain of the 'auditor's' bit.
'auditor's game' is the wordplay.
'auditor' becomes 'checker'.
'game' becomes 's' (I can't explain this - if you can you should believe this answer much more).
'checker'+'s'='CHECKERS'
Can you help me to learn more?
(Other definitions for checkers that I've seen before include "Quality assurance personnel" , "They scrutinise" , "Draughts in America" , "American game" , "those on board" .)