Shutter protecting lens (6)

I believe the answer is:

eyelid

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This clue might be a double definition.

'shutter protecting' is the first definition.
'eyelid' can be an answer for 'shutter' (I have seen 'Facial shutter' mean 'eyelid' so perhaps 'shutter' could also mean 'eyelid'). I am not sure about the 'protecting' bit.

'lens' is the second definition.
(thesaurus)

Can you help me to learn more?

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

I've seen this clue in The Sunday Times.

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