Vote to change ban (4)
I believe the answer is:
veto
'ban' is the definition.
(veto can mean a ban or prohibition on something)
'vote to change' is the wordplay.
'to change' indicates an anagram.
'vote' is an anagram of 'VETO'.
(Other definitions for veto that I've seen before include "Reject - ban" , "Authoritative prohibition" , "Ban; refuse to allow" , "Don't allow" , "Refuse to endorse" .)