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

I believe the answer is:

nails

I'm a little stuck... Click here to teach me more about this clue!

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

I cannot understand how the rest of the clue works.

(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.

Want a hint initially instead of a full solution? Install my app