Old English silver coin worth four pennies (5)
I believe the answer is:
groat
'old english silver coin worth four pennies' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for groat that I've seen before include "Old English coin worth four pennies" , "Old coin worth four pence" , "Old four-pence coin" , "Old fourpenny coin" , "Medieval coin" .)