A sound or two, almost one gun, maybe not one (5)
I believe the answer is:
twang
'a sound' is the definition.
(twang is a kind of sound)
'two almost one gun maybe not one' is the wordplay.
I cannot really understand how this works, but
'one' could be 'an' (I've seen this in other clues) and 'an' is found within the answer.
This explanation may well be incorrect...
'or' is the link.
Can you help me to learn more?
(Other definitions for twang that I've seen before include "way of speaking" , "Regional intonation" , "ringing sound" , "Nasal accent" , "nasal effect" .)