Onionlike vegetable (4)
I believe the answer is:
leek
'onionlike vegetable' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for leek that I've seen before include "Green and white vegetable" , "Plant (onion relative) eaten as a vegetable" , "Bulb" , "Plant related to the onion, pair with potato for soup" , "what Fluellen wore in France?" .)