Add water to bouquet (5)
I believe the answer is:
spray
'bouquet' is the definition.
(thesaurus)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for spray that I've seen before include "Treat with insecticide etc" , "Disperse in tiny drops" , "Aerosol efflux" , "Finely sprinkle" , "posy of flowers" .)