Workers here are constantly striking (5)

I believe the answer is:

anvil

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'workers here are constantly striking' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.

This is the entire clue.

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(Other definitions for anvil that I've seen before include "Bone" , "Smithy's last" , "Block used in forge" , "Block for metalworking" , "Forging block" .)

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

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