Eye part with the iris (4)
I believe the answer is:
uvea
'eye part with the iris' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for uvea that I've seen before include "Iris's part" , "Part of the eyeball which houses the iris" , "bit of mince pie!" , "Pigmented part of eye" , "The pigmented layer of the eye" .)