Registered grand French monarch (3,4)

I believe the answer is:

sun king

This clue might be a double definition.

'registered grand french' is the first definition.
The definition suggests an adjective which matches the answer.

'monarch' is the second definition.
(I know that Sun King is a King of France)

(Another definition for sun king that I've seen is " Epithet of Louis XIV of France".)

I've seen this clue in The Times.

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