Chest expanders for servicemen? (6)

I believe the answer is:

medals

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'servicemen?' is the definition.
Although both the answer and definition are plural nouns, I cannot see how one could define the other.

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for medals that I've seen before include "Metal discs given as awards" , "Awards for damsel" , "Gongs" , "Military decorations" , "Small metal discs as awards - think Olympic games" .)

I've seen this clue in the Evening Standard.

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