Rough edges on large cutting tool (6)
I believe the answer is:
sickle
'cutting tool' is the definition.
(sickle is a kind of cutting tool)
'rough edges on large' is the wordplay.
'rough' becomes 'sick' (both can mean unwell).
'edges on' means to remove the middle letters.
'large' with its centre removed is 'le'.
'sick'+'le'='SICKLE'
(Other definitions for sickle that I've seen before include "Cutting farming tool" , "Farmer's tool" , "Edge tool" , "Grass-cutting implement" , "Reaping hook" .)