It comes out of the barrel, but it's news when it gets in! (6)
I believe the answer is:
bullet
'it comes out of the barrel' is the definition.
The definition suggests a singular noun which matches the answer.
'but it's news when it gets in' is the wordplay.
'it's news when' becomes 'll' (I am not sure about this - if you are sure you should believe this answer much more).
'it' becomes 'e' ('e' can mean 'electronic' which is similar to 'IT').
'gets in' indicates putting letters inside.
'll'+'e'='lle'
'but' placed around 'lle' is 'BULLET'.
Can you help me to learn more?
(Other definitions for bullet that I've seen before include "Piece of ammunition" , "Lethal projectile" , "Projectile ammunition" , "Something fast moving" , "Small missile from gun" .)