They have to be driven home (5)
I believe the answer is:
nails
'they' is the definition.
Both the definition and answer are plural nouns.
Perhaps there's an association between them I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for nails that I've seen before include "Metal fasteners" , "Horny plates of the digits" , "Horny plates and pointed pins" , "Slain with metal pins" , "Fixing pins" .)