A colour between green and red (5)

I believe the answer is:

amber

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'a colour' is the definition.
(amber is a kind of colour)

I don't understand the rest of the clue.

(Other definitions for amber that I've seen before include "first light" , "Honey-yellow colour" , "warning signal" , "Light colour between red and green" , "Ornamental fossil resin" .)

I've seen this clue in The Irish News.

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