Bart turned out to be naughty youngster (4)

I believe the answer is:

brat

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'naughty youngster' is the definition.
'brat' can be an answer for 'youngster' (brat is a kind of youngster). I'm not sure about the 'naughty' bit.

'bart turned out' is the wordplay.
'turned out' indicates anagramming the letters.
'bart' is an anagram of 'BRAT'.

'to be' is the link.

Can you help me to learn more?

(Other definitions for brat that I've seen before include "A spoiled badly-behaved child" , "Bad child - pack member!" , "Troublesome child" , "Mervyn -- (Titus Groan)" , "Horrible child" .)

I've seen this clue in The Mirror.

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