Crossword Genius

Radiant source: that's our paper! (3)

Ross

I believe the answer is:

sun

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'paper' is the definition.
(The Sun, UK newspaper)

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for sun that I've seen before include "Centre of Earth's orbit" , "Source of light and heat" , "Bask" , "Earth's nearest star" , "Warmer" .)

I've seen this clue in The Sun.
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