Head offset auditor (4,7)
I believe the answer is:
bean counter
'auditor' is the definition.
I know nothing about this answer so I can't tell whether this works.
'head offset' is the wordplay.
'head' becomes 'bean' (bean is a kind of head).
'offset' becomes 'counter' (I can't explain this - if you can you should give a lot more credence to this answer).
'bean'+'counter'='BEAN-COUNTER'
Can you help me to learn more?
(Other definitions for bean counter that I've seen before include "Accountant (slang)" , "stingy financial official?" , "Cost-conscious bureaucrat" , "who worries about finances?" , "Accountant, colloquially" .)