Five keys and a distinguishing emblem (5)

I believe the answer is:

badge

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'distinguishing emblem' is the definition.
(a badge is an emblem or sign)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for badge that I've seen before include "Lapel emblem" , "Emblem of belonging" , "Distinguishing symbol" , "Emblem of office" , "Emblem signifying rank, membership etc" .)

I've seen this clue in The Daily Express.

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