One who hears and sums up all the accounts (7)

I believe the answer is:

auditor

I'm a little stuck... Click here to teach me more about this clue!

'one who hears' is the definition.
(I've seen this before)

I don't understand how the remainder of the clue works.

(Other definitions for auditor that I've seen before include "Listener; checker" , "One inspects the accounts" , "He checks the account books annually" , "Accountant - listener" , "Person who listens" .)

I've seen this clue in The Globe and Mail.

Want a hint initially instead of a full solution? Install my app