Vegetable associated with Wales (4)
I believe the answer is:
leek
'vegetable associated with wales' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for leek that I've seen before include "Plant (onion relative) eaten as a vegetable" , "Staffordshire town?" , "Onion's relative" , "Vegetable related to the onion" , "Green and white vegetable" .)