Rough edge (4)
I believe the answer is:
burr
'rough edge' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for burr that I've seen before include "Rough projection left after cutting" , "Seed vessel" , "rough feature of dialect" , "Accent, maybe Northumbrian or West Country" , "Sticky seed pod" .)