Graduate tax upset vote (6)
I believe the answer is:
ballot
'vote' is the definition.
(balloting is a kind of voting)
'graduate tax upset' is the wordplay.
'graduate' becomes 'ba'.
'tax' becomes 'toll' (I've seen this in other clues).
'upset' says the letters should be written in reverse.
'toll' in reverse letter order is 'llot'.
'ba'+'llot'='BALLOT'
(Other definitions for ballot that I've seen before include "Vote or suffrage" , "Single or collective vote" , "Secret vote" , "Document listing voting alternatives" , "Poll" .)