A near-sighted gathering (4)

I believe the answer is:

stye

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'a near-sighted gathering' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.

This is the entire clue.

Can you help me to learn more?

(Other definitions for stye that I've seen before include "producing eyesore" , "Climb" , "Seeing problem" , "Viewer's complaint" , "Eye sore" .)

I've seen this clue in The Globe and Mail.

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