Do away with unlimited tariffs (3)

I believe the answer is:
axe
'do away with' is the definition.
(I've seen this before)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for axe that I've seen before include "Means of cutting" , "Eliminate" , "Chopping tool with heavy blade" , "Cut (jobs)" , "can bring down plane" .)
