Cheese sandwiches — admit marks as award for good deeds (7,6)
I believe the answer is:
brownie points
'award for good deeds' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'cheese sandwiches admit marks' is the wordplay.
'cheese' becomes 'brie' (Brie is an example).
'sandwiches' is an insertion indicator (to sandwich is to block something in).
'admit' becomes 'own' (own can mean to admit or acknowledge).
'marks' becomes 'points' (point is a kind of mark).
'brie' going around 'own' is 'brownie'.
'brownie'+'points'='BROWNIE POINTS'
'as' acts as a link.
Can you help me to learn more?
(Other definitions for brownie points that I've seen before include "Credit for doing well" , "Marks gained for good behaviour" , "approbation" , "Marks earned for doing right?" , "Notional credit marks" .)