Single payment (4,3)
I believe the answer is:
lump sum
'single payment' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for lump sum that I've seen before include "11 [LOLLY] as single amount" , "Large payment, often in cash" , "one lot of money" , "Single amount of money" , "chunk of bread?" .)