Petition for vote against stuck up Americans (7)
I believe the answer is:
yankees
'americans' is the definition.
(Yankee can informally mean an American)
'petition for vote against stuck up' is the wordplay.
'petition for' becomes 'seek' (I can't explain this - if you can you should give a lot more credence to this answer).
'vote against' becomes 'nay' (as in aye or nay).
'stuck up' says the letters should be written in reverse.
'seek'+'nay'='seeknay'
'seeknay' back-to-front is 'YANKEES'.
Can you help me to learn more?
(Other definitions for yankees that I've seen before include "US Civil War soldiers" , "Northern soldiers in the American Civil War" , "Union troops" , "Side in US Civil War" , "Americans (sl.)" .)