Blue-blooded boy by another name (5)

I believe the answer is:

royal

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'blue' is the definition.
(royal blue is a kind of blue)

I don't understand the rest of the clue.

(Other definitions for royal that I've seen before include "As kings and queens" , "Referring to the sovereign" , "August" , "Relating to a monarch" , "Queen Mary, for example" .)

I've seen this clue in the Evening Standard.

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