Stop people from seeing small, erotic image (10)

I believe the answer is:

screenshot

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'stop people from' is the definition.
I don't know anything about this answer so I cannot judge whether this works.

'small erotic image' is the wordplay.
'small erotic' becomes 'screen' (I can't explain this - if you can you should believe this answer much more).
'image' becomes 'shot' (shot is a kind of image).
'screen'+'shot'='SCREENSHOT'

'seeing' is the link.

Can you help me to learn more?

I've seen this clue in The Guardian.

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