Straw vote (4)
I believe the answer is:
'straw vote' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for poll that I've seen before include "Means of ascertaining public opinion with questions" , "coverage of vote for 9d > [WHISTLE BLOWER]" , "A vote; a head" , "Voting as at an election" , "Votes cast at an election" .)