Excluding line from fashion causes visual problem (4)
I believe the answer is:
stye
'problem' is the definition.
The definition and answer can be both states of affairs as well as being singular nouns.
Maybe you can see a link between them that I can't see?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for stye that I've seen before include "Infection on the edge of the eye" , "producing eyesore" , "Tamworth residence" , "Eyelid sore" , "Eye problem" .)