Eye irritation (4)
I believe the answer is:
stye
'eye irritation' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for stye that I've seen before include "Ocular inflammation" , "Eyelid problem" , "Inflamed swelling on the edge of an eyelid" , "Ocular affliction" , "producing eyesore" .)