Money business (7)
I believe the answer is:
banking
'money business' is the definition.
'banking' can be an answer for 'business' (banking is a kind of business). I also know that 'money' relates to this answer.
This is all the clue.
(Other definitions for banking that I've seen before include "Relying" , "(Of aircraft) turning" , "financial activity" , "Depositing and withdrawing money" , "Engaging in the business of depositing and lending money" .)