Fastened securely with a pointed piece of metal (6)
I believe the answer is:
nailed
'fastened securely with a pointed piece of metal' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for nailed that I've seen before include "Fixed; lead in (anag.)" , "Caught, collared" , "Attached by means of a pointed piece of metal" , "Fastened by Daniel" , "Fixed with a spike" .)