Opinion survey (4)
I believe the answer is:
poll
'opinion survey' 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 "Record of opinions" , "Take away" , "Head; register of voters" , "coverage of vote for 9d > [WHISTLE BLOWER]" , "A vote; a head" .)