One injected acidly? (5)

I believe the answer is:

sting

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'one' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for sting that I've seen before include "Smart - swindle" , "(Bee) wound" , "Painful wound - confidence trick" , "Carefully planned trap - scorpion's weapon" , "fraud" .)

I've seen this clue in the Evening Standard.

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