Fourpence for roll first covered with butter (5)
I believe the answer is:
groat
'fourpence' is the definition.
('groat' can be a synonym of 'fourpence')
'roll first covered with butter' is the wordplay.
'first' says to take the initial letters.
'covered with' means one lot of letters goes inside another.
'butter' becomes 'goat' (a goat is a butt-er).
The first letter of 'roll' is 'r'.
'r' going into 'goat' is 'GROAT'.
'for' is the link.
(Other definitions for groat that I've seen before include "Old fourpenny coin" , "Fourpenny piece" , "Old English silver coin" , "Medieval coin" , "Old four-pence coin" .)