Old viewers start to yawn during evening of poetry (4)

I believe the answer is:

eyne

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'old' is the definition.
Both the answer and definition are singular nouns.
Perhaps they are linked in a way I don't understand?

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for eyne that I've seen before include "Once they saw" , "very old viewers" .)

I've seen this clue in The Times and The Sunday Times.

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