Proper nozzle for watering a flower (8)
I believe the answer is:
primrose
'a flower' is the definition.
(thesaurus)
'proper nozzle for watering' is the wordplay.
'proper' becomes 'prim' ('prim' can be similar in meaning to 'proper').
'nozzle for watering' becomes 'rose' (term for the nozzle on a watering can).
'prim'+'rose'='PRIMROSE'
(Other definitions for primrose that I've seen before include "Pale yellow- a primula" , "Pale yellow flower" , "something in the bed!" , "Woodland plant with pale yellow flowers" , "Woodland plant with yellow flowers in spring" .)