Yap about sweeper's revenge (7)
I believe the answer is:
payback
'revenge' is the definition.
(I know that payback is a type of revenge)
'yap about sweeper's' is the wordplay.
'about' shows that the letters should be reversed in order.
'sweeper's' becomes 'back' (I can't justify this - if you can you should believe this answer much more).
'yap' backwards is 'pay'.
'pay'+'back'='PAYBACK'
Can you help me to learn more?
(Other definitions for payback that I've seen before include "Profit" , "Financial return" , "return on investment" , "act of revenge" .)