The most common and most likely answer to this crossword clue is the 7 letter word PUCKISH
I've seen this crossword clue in Financial Times
P
U
C
K
I
S
H
More clues leading to the result PUCKISH
Buddy explains!

The straight part
We know that "naughty" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case naughty = puckish.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.
What does PUCKISH mean?
PUCKISH adjective- Mischievous; excessively playful.