Furlong fraction (4)
I believe the answer is:
yard
'furlong fraction' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for yard that I've seen before include "quantity of ale" , "A little under a metre" , "Enclosed area; length" , "Unit of length; enclosure" , "Enclosed area by building - old measure" .)