Harm in boasting symbol of ownership (4-4)

I believe the answer is:

swan-mark

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'ownership' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.

'harm in boasting symbol' is the wordplay.
'harm' becomes 'mar' (I've seen this before).
'in' is an insertion indicator.
'boasting symbol' becomes 'swank' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'mar' put into 'swank' is 'SWAN-MARK'.

'of' is the link.

Can you help me to learn more?

I've seen this clue in The Independent.

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