Dismissal of missile (6)
I believe the answer is:
bullet
This clue might be a double definition.
'dismissal' is the first definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'missile' is the second definition.
(bullet is a kind of missile)
'of' acts as a link.
Can you help me to learn more?
(Other definitions for bullet that I've seen before include "Something fast moving" , "Gun projectile" , "Lethal projectile" , "Revolver missile" , "Slug" .)