Bone, say, is stewed with this vegetable (7)
I believe the answer is:
soybean
'this vegetable' is the definition.
(soybean is a kind of vegetable)
'bone say is stewed' is the wordplay.
'is stewed' indicates anagramming the letters.
'bone'+'say'='bonesay'
'bonesay' is an anagram of 'SOYBEAN'.
'with' acts as a link.
(Other definitions for soybean that I've seen before include "Vegetable source of protein" , "American vegetable" .)