Her mother's beautiful, too (5)

I believe the answer is:

pearl

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'her' is the definition.

I cannot understand how the rest of the clue works.

(Other definitions for pearl that I've seen before include "Lustrous structure inside an oyster-shell" , "something highly valued" , "White - jewel" , "Gem from oyster" , "Off-white colour" .)

I've seen this clue in the Evening Standard.

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