Crossword Genius

Go to prison? One's a shining light (6)

Ross

I believe the answer is:

beacon

'shining light' is the definition.
(a beacon is a bright light)

I cannot understand how the remainder of the clue works.

(Other definitions for beacon that I've seen before include "Prominent light on a hill" , "Navigational guide" , "Fire on a hill, lit as a signal" , "Warning fire or signal" , "A warning light as on headland" .)

I've seen this clue in The Guardian.
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