Cash difference (6)
I believe the answer is:
change
I believe this clue is a double definition.
'cash' is the first definition.
(I know that change is a type of cash)
'difference' is the second definition.
(I know that change is a type of difference)
(Other definitions for change that I've seen before include "Loose money in pocket" , "Redesign" , "Put on different clothes" , "Best not to do it in 12" , "Alter for small coins" .)