One has an eye for beauty, they say (8)

I believe the answer is:

beholder

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'one' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.

I can't explain the rest of the clue.

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(Other definitions for beholder that I've seen before include "Observer" , "Witness" , "there's beauty in her eyes" , "Some looker" , "Onlooker" .)

I've seen this clue in The Guardian.

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