Catches slow folk, heading off (5)
I believe the answer is:
nails
'catches' is the definition.
(I've seen this in another clue)
'slow folk heading off' is the wordplay.
'slow folk' becomes 'snails' (snail can mean a slow person).
'heading off' means to remove the first letter.
'snails' with its first letter taken away is 'NAILS'.
(Other definitions for nails that I've seen before include "measure of hardness?" , "Fixing spikes" , "Horny plates and pointed pins" , "Horny plates of the digits" , "Metal spikes" .)