Cut severely! (5)
'cut' is the definition.
(to sever is to cut or split)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for sever that I've seen before include "Cut right off" , "Cut from a whole" , "Cut apart, maybe a relationship" , "Lop off" , "Divide, cut" .)
(Other definitions for axed that I've seen before include "Abandoned, given the chop" , "Discontinued with hatchet?" , "removed" , "Made redundant" , "Abandoned project using chopper" .)