XII, say, to cut out (6)
I believe the answer is:
excise
'cut out' is the definition.
(I've seen this in other clues)
I can't explain the rest of the clue.
(Other definitions for excise that I've seen before include "Cut out; commodity tax" , "Duty; cut out" , "Internal tax" , "that wretches hatefully collect" , "Remove by cutting out" .)