Crossword Genius

Royal Mile beggar developing brazen guile (11)

Ross

I believe the answer is:

gaberlunzie

I'm a little stuck... Click here to teach me more about this clue!

'royal' is the definition.
Both the definition and answer are singular nouns.
Perhaps they are linked in a way I don't understand?

I cannot understand how the rest of the clue works.

Can you help me to learn more?

I've seen this clue in The Times and The Sunday Times.
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