Annoyance to the royals? That's heartless and unkind (4)

I believe the answer is:

mean

'unkind' is the definition.
(I've seen this before)

I don't understand the rest of the clue.

(Other definitions for mean that I've seen before include "'Midway, average (4)'" , "middle course" , "spell" , "Spiteful -- excellent (slang)" , "Common" .)

I've seen this clue in The Guardian.

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