One in Einstein's family? (8)

I believe the answer is:

relative

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'family?' is the definition.
(I know that family can be written as relative)

I don't understand the remainder of the clue.

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(Other definitions for relative that I've seen before include "Granny, perhaps" , "Person connected by blood or marriage" , "One connected by blood or marriage" , "Sort of pronoun" , "Grandad perhaps" .)

I've seen this clue in the Evening Standard.

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