If rifle’s fired, echo’s interrupting insects (9)

I believe the answer is:

fireflies

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'if rifle's fired echo's' is the definition.
I can't tell whether this definition defines the answer.

'interrupting insects' is the wordplay.
'interrupting' becomes 'fire' (I am not sure about this - if you are sure you should believe this answer much more).
'insects' becomes 'flies' (fly is a kind of insect).
'fire'+'flies'='FIREFLIES'

Can you help me to learn more?

I've seen this clue in The Hindu.

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