Tool with arched blade set at right angles (4)
I believe the answer is:
adze
'tool with arched blade set at right angles' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for adze that I've seen before include "Cutting tool with arched blade" , "Tool for shaping large pieces of wood" , "Axe-like tool" , "Dresser" , "Wood cutting tool" .)