Make an opening in part of the gun, we hear (6)
I believe the answer is:
breach
'make an opening' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'part of the gun we hear' is the wordplay.
I cannot really understand how this works, but
'part' could be 'reach' (reach is a kind of part) and 'reach' is found in the answer.
A single letter 'b' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'in' acts as a link.
Can you help me to learn more?
(Other definitions for breach that I've seen before include "Failure to follow the rules" , "Break (in a wall, etc)" , "Violation of a promise" , "'A custom more 1 down in the ____ ..." , "Non-observance" .)