Choose to veto, perhaps (4)
I believe the answer is:
vote
'choose' is the definition.
(voting is a kind of choosing)
'veto perhaps' is the wordplay.
'perhaps' is an anagram indicator.
'veto' is an anagram of 'VOTE'.
'to' acts as a link.
(Other definitions for vote that I've seen before include ""X" marked on election day" , "Elector's choice" , "Put one's cross" , "Decision by a majority" , "Mark an 'X'" .)