Tool does some calculations, we’re told (4)
I believe the answer is:
adze
'tool' is the definition.
(adze is a kind of tool)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for adze that I've seen before include "Woodworker's tool" , "One might cut" , "Wood cutting tool" , "Carpenter's tool sounds mathematical" , "One cuts" .)