After reflecting, one declines to go into Vauxhall plant (10)
I believe the answer is:
aspidistra
'plant' is the definition.
(aspidistra is a kind of plant)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for aspidistra that I've seen before include "For Asian native" , "The biggest - (in the world) (Gracie Fields)" , "Plant of the lily family" , "Large houseplant" , "Huge house plant" .)