Tweak for coppers (5,6)
I believe the answer is:
small change
This clue is a double definition.
'tweak' is the first definition.
(a tweak is a small change)
'coppers' is the second definition.
(as in copper coins)
'for' acts as a link.
(Other definitions for small change that I've seen before include "Chickenfeed" , "Things are much the same" , "Coins of low value" , "Money" , "Not much difference" .)