gusty (5)
I believe the answer is:
'gusty' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for windy that I've seen before include "Timid - tempestuous" , "Gusty" , "Blowy" , "Frightened - not still" , "Conceited - nervous - registering on the Beaufort scale" .)