Member of the penguin family? (7)

I believe the answer is:

flipper

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'member' is the definition.
(I know that flipper is a type of Forelimb)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for flipper that I've seen before include "Seal/turtle limb" , "provision for diver" , "Dolphin's limb" , "Limb used for swimming" , "Shoe for swimming" .)

I've seen this clue in The Independent.

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