Hammers' targets (5)
I believe the answer is:
nails
'hammers' targets' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for nails that I've seen before include "they may provide security for the board" , "Slain with metal pins" , "Metal spikes" , "Fastens with spikes" , "Metal fasteners" .)