Crossword Genius

Veto (8)

Ross

I think it could be either:

prohibit

overrule

(Other definitions for overrule that I've seen before include "Prevail over - disallow" , "Disallow from a superior position" , "Reject (decision) using superior authority" , "Reverse another's decision" , "Turn down (objection)" .)

I've seen this clue in the Sydney Morning Herald and the LA Times.
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