A vegetable vessel (5)
I believe the answer is:
gourd
This clue could be a double definition.
'a vegetable' is the first definition.
The definition and answer can be both plants as well as being singular nouns.
Maybe you can see a link between them that I don't see?
'vessel' is the second definition.
(gourd is a kind of vessel)
Can you help me to learn more?
(Other definitions for gourd that I've seen before include "Hard-skinned fruit" , "Plant related to the pumpkin, squash and cucumber" , "Fleshy fruit" , "Fruit akin to pumpkin" , "Bottle, dishcloth, plant" .)