A large weapon creates fear (5)
I believe the answer is:
alarm
'fear' is the definition.
(alarm is a kind of fear)
'a large weapon' is the wordplay.
'large' becomes 'l'.
'weapon' becomes 'arm' (I've seen this before).
'a'+'l'+'arm'='ALARM'
'creates' is the link.
(Other definitions for alarm that I've seen before include "It signals danger" , "Frighten, scare" , "Tocsin" , "Alternative to reveille" , "Agitate" .)