Sightscreen? (6)

I believe the answer is:

eyelid

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'sightscreen?' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see an association between them that I can't see?

This is all the clue.

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(Other definitions for eyelid that I've seen before include "Ocular shutter" , "It's used in blinking" , "Object of batting" , "Cover for viewer" , "Facial shutter" .)

I've seen this clue in The Irish Independent.

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