In Vogue dismissing upstart in the forest (6)
I believe the answer is:
poplar
'in' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for poplar that I've seen before include "The tree is almost liked" , "Tree - London district" , "Leaves producer" , "Slender tree with quivering leaves" , "Tall tree (which may tremble?)" .)