Member of the royal family whose titles include Earl of Dumbarton and Baron Kilkeel (6,5)

'family whose titles include earl of dumbarton and baron kilkeel' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'member of the royal' is the wordplay.
I cannot really see how this works, but
'royal' could be 'prince' (prince is a kind of royal) and 'prince' is found in the answer.
The remaining letters 'harry' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?