Soup green (3)
I believe the answer is:
pea
I believe this clue is a double definition.
'soup' is the first definition.
(pea soup is a kind of soup)
'green' is the second definition.
(pea green is a kind of green)
(Other definitions for pea that I've seen before include "Climbing plant; vegetable" , "It grows in 23 Down" , "Edible green seed" , "It grows in a pod" , "veg" .)