Unfamiliar, a claim on property (5)

I believe the answer is:

alien

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

'a claim on property' is the wordplay.
'claim on property' becomes 'lien' (I can't explain this - if you can you should give a lot more credence to this answer).
'a'+'lien'='ALIEN'

Can you help me to learn more?

(Other definitions for alien that I've seen before include "Offensive" , "Outlandish" , "Foreign (from outer space?)" , "Belonging to a foreign country" , "immigrant" .)

I've seen this clue in The Telegraph.

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