The sunfish? (3)

I believe the answer is:

ray

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'the sunfish?' is the definition.
The answer and definition can be both animals as well as being singular nouns.
Maybe there's an association between them I don't understand?

This is all the clue.

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(Other definitions for ray that I've seen before include "Narrow beam of light" , "Flatfish or sunbeam" , "beamer?" , "Beam of light or flat fish" , "Column of light on the fish?" .)

I've seen this clue in the Evening Standard.

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