My pence will make pound (4)
I believe the answer is:
coop
'pound' is the definition.
(I've seen this before)
'my pence' is the wordplay.
'my' becomes 'coo' (both are expressions of surprise).
'pence' becomes 'p'.
'coo'+'p'='COOP'
'will make' is the link.
(Other definitions for coop that I've seen before include "Store" , "Birdcage" , "Pen" , "Cage for poultry" , "pound" .)