Part of eye with ear, ear cut (6)
I believe the answer is:
cornea
'part of eye' is the definition.
(I know that cornea is part of eye)
'with ear ear cut' is the wordplay.
'with' says to put letters next to each other.
'ear' becomes 'corn' (as in an ear of corn).
'cut' means to remove the last letter.
'ear' with its last letter taken away is 'ea'.
'corn'+'ea' is 'CORNEA'.
(Other definitions for cornea that I've seen before include "Transparent outer covering of eyeball" , "Front covering of eye" , "Eyeball membrane" , "Transparent part of the eye" , "Outer covering of the eye" .)