Ring-shaped membrane in the eye (4)
I believe the answer is:
iris
(Other definitions for iris that I've seen before include "Eye diaphragm" , "is 21[WOMAN], perhaps" , "Flag,flower and part of the eye" , "Flower - girl's name" , "Female" .)
I believe the answer is:
iris
(Other definitions for iris that I've seen before include "Eye diaphragm" , "is 21[WOMAN], perhaps" , "Flag,flower and part of the eye" , "Flower - girl's name" , "Female" .)