Cornea coverer (6)
I believe the answer is:
eyelid
'cornea coverer' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for eyelid that I've seen before include "It's used in blinking" , "Cover for cornea" , "Blinking cover" , "Facial shutter" , "Skin for blinking" .)