Cover evidence of firearm usage in computer image (10)

I believe the answer is:

screenshot

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'cover evidence of firearm usage' is the definition.
I know nothing about this answer so I cannot judge whether this works.

'computer image' is the wordplay.
'computer' becomes 'screen' (I am not sure about this - if you are sure you should believe this answer much more).
'image' becomes 'shot' (shot is a kind of image).
'screen'+'shot'='SCREENSHOT'

'in' acts as a link.

Can you help me to learn more?

I've seen this clue in The Times.

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