Cheeky kids steal a fish (15)

I believe the answer is:

whippersnappers

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'cheeky kids' is the definition.
The answer and definition can be both people as well as being plural nouns.
Perhaps there's an association between them I don't understand?

'steal a fish' is the wordplay.
'steal' becomes 'whip' (I've seen this before).
'a' becomes 'per' (eg 'one a day' means 'one per day').
'fish' becomes 'snappers' (I've seen this before).
'whip'+'per'+'snappers'='WHIPPERSNAPPERS'

Can you help me to learn more?

(Another definition for whippersnappers that I've seen is " Youths showing cheek".)

I've seen this clue in The Sunday Times and The Times.

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