Spike, catch! (4)
I believe the answer is:
nail
This clue is a double definition.
'spike' is the first definition.
(I've seen this before)
'catch' is the second definition.
(nail can mean to catch or arrest)
(Other definitions for nail that I've seen before include "Metal fastener" , "thing for keeping things together" , "Finger feature (and tooth?)" , "for the carpenter?" , "Fixing pin" .)