Use an aerosol (5)
I believe the answer is:
'use an aerosol' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for spray that I've seen before include "jet?" , "Bunch of flowers" , "Squirt water" , "Disperse in tiny drops" , "Sprinkle water on - a small bouquet" .)