What one might do on a windy day to test opinion (3,1,4)
I believe the answer is:
fly a kite
I'm afraid I can't even guess how this answer relates to the clue.
Can you help me to learn more?
(Other definitions for fly a kite that I've seen before include "What co-pilots do" , "Pilot" , "Release information to test public opinion" , "Test opinion by circulating rumours" .)