Vegetable king stuffed into nozzle (6)
I believe the answer is:
sprout
'vegetable' is the definition.
(sprout is a type of vegetable)
'king stuffed into nozzle' is the wordplay.
'king' becomes 'R' (abbreviation for rex, king in Latin).
'stuffed into' is an insertion indicator.
'nozzle' becomes 'spout' (I've seen this in another clue).
'r' placed into 'spout' is 'SPROUT'.
(Other definitions for sprout that I've seen before include "Develop new growth" , "Push out new shoots" , "Begin to develop" , "Grow like Proust" , "Put out shoots for the vegetable" .)