A pronounced contribution to radiation (3)

I believe the answer is:

ray

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'radiation' is the definition.
(ray is a kind of radiation)

I cannot understand how the rest of the clue works.

(Other definitions for ray that I've seen before include "Beam; man's name" , "Beam of light or flat fish" , "A little light" , "Broad flat fish; beam" , "Second note for the flat fish" .)

I've seen this clue in the Evening Standard.

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