Wildfowlers besiege a French plant (9)
I believe the answer is:
sunflower
'wildfowlers' is the definition.
I can't tell whether this definition defines the answer.
'besiege a french plant' is the wordplay.
'besiege a french' becomes 'sun' (I am not sure about this - if you are sure you should believe this answer much more).
'plant' becomes 'flower' (flower is a kind of plant).
'sun'+'flower'='SUNFLOWER'
(Other definitions for sunflower that I've seen before include "seen in Van Gogh's art" , "Plant's" , "Source of oil" , "that Van Gogh used to paint" , "nickname of US State" .)