Weeds cooked as a vegetable (5)
I believe the answer is:
swede
'a vegetable' is the definition.
(swede is a kind of vegetable)
'weeds cooked' is the wordplay.
'cooked' is an anagram indicator.
'weeds' is an anagram of 'SWEDE'.
'as' is the link.
(Other definitions for swede that I've seen before include "Scandinavian; root veg." , "Large root vegetable" , "Citizen of kingdom" , "A turnip, or a Scandinavian" , "Foreigner" .)