I cram its design into a weapon (8)
I believe the answer is:
scimitar
'a weapon' is the definition.
(scimitar is a kind of weapon)
'i cram its design' is the wordplay.
'design' is an anagram indicator.
'i'+'cram'+'its'='icramits'
'icramits' is an anagram of 'SCIMITAR'.
'into' is the link.
(Other definitions for scimitar that I've seen before include "This cut" , "Curved form of sword" , "Curved oriental sabre" , "sharp weapon" , "Eastern sword" .)