With which to see a flower (4)
I believe the answer is:
iris
I believe this is a double definition.
'with which to see' is the first definition.
(part of the eye)
'a flower' is the second definition.
(iris is a type of flower)
(Other definitions for iris that I've seen before include "Plant with sword-shaped leaves" , "bit of a looker" , "Film about writer _______ Murdoch" , "Flag - part of eye" , "Flag - surrounding pupil" .)