Smith’s property under the hammer? (5)

I believe the answer is:

anvil

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'the hammer?' is the definition.
(thesaurus)

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

(Other definitions for anvil that I've seen before include "hard block" , "Block in smithy" , "Forging block" , "Iron block; incus" , "part of the ear" .)

I've seen this clue in the Evening Standard.

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