Choose to veto plan (4)
I believe the answer is:
vote
'choose' is the definition.
(I know that vote is a more specific form of choose)
'veto plan' is the wordplay.
'plan' is an anagram indicator (plan can mean organise).
'veto' with letters rearranged gives 'VOTE'.
'to' acts as a link.
(Other definitions for vote that I've seen before include "Ballot, exercise of franchise" , "Register one's choice" , "Plebiscite" , "Take part in an election" , "Indicate choice in an election" .)