They may be pierced or just pricked (4)

I believe the answer is:

ears

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'they' is the definition.
Both the answer and definition are plural nouns.
Perhaps you can see an association between them that I don't see?

I don't understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for ears that I've seen before include "Spikes of corn" , "Heads of corn" , "Lugs (colloq.)" , "Listening organs" , "Auricles" .)

I've seen this clue in The Globe and Mail.

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