Painful injections (6)

I believe the answer is:

stings

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'painful injections' is the definition.
The definition and answer can be both acts as well as being plural nouns.
Perhaps there's a link between them I don't understand?

This is all the clue.

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(Other definitions for stings that I've seen before include "Confidence tricks by the bee?" , "Bee bites" , "Confidence tricks, swindles" , "Insect bites" , "Hurts like bee or wasp" .)

I've seen this clue in the Evening Standard.

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