Wrong veto, right elector (5)
I believe the answer is:
voter
'elector' is the definition.
(I know that elector can be written as voter)
'wrong veto right' is the wordplay.
'wrong' is an anagram indicator.
'right' becomes 'r' (abbreviation).
'veto' with letters rearranged gives 'vote'.
'vote'+'r'='VOTER'
(Other definitions for voter that I've seen before include "supporter of politician" , "Lively dances (esp. Irish)" , "Overt (anag)" , "one making sign of the cross" , "Elector" .)