Cryptic crossword clue
Very troublesome child, somehow hotly pursued by mistake 4,6

The most common and most likely answer to this crossword clue is the 4 plus 6 letter word HOLY TERROR

I've seen this crossword clue in Financial Times
H
O
L
Y
T
E
R
R
O
R

Buddy explains!

The straight part
We know that "Very troublesome child," is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case very troublesome child, = holy terror.
The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.
This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.

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