Shutter closed when sleeping (6)

I believe the answer is:

eyelid

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'shutter' is the definition.
(I have seen 'Facial shutter' mean 'eyelid' so perhaps 'shutter' could also mean 'eyelid')

I don't understand the remainder of the clue.

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(Other definitions for eyelid that I've seen before include "One winks with it" , "It may be batted" , "Cover for viewer" , "Cover for organ of sight" , "Object of batting" .)

I've seen this clue in The Times.

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