Sluggish individual letting down society - they're hammered (5)

I believe the answer is:

nails

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'they're hammered' is the definition.
(nails are hammered)

I don't understand the remainder of the clue.

(Other definitions for nails that I've seen before include "Metal spikes" , "Fixing spikes" , "Fixes" , "Slain with metal pins" , "Claws" .)

I've seen this clue in The Independent.

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