Sack for someone who takes money (7)
I believe the answer is:
cashier
This clue might be a double definition.
'sack' is the first definition.
(I've seen this before)
'someone who takes money' is the second definition.
'cashier' can be an answer for 'someone' (cashier is a kind of someone). I am not certain of the rest of the definition.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for cashier that I've seen before include "may be a shop-worker" , "Fire" , "One handles the money" , "Dismiss (someone) from the armed forces in disgrace" , "employee accepting money" .)