The most common and most likely answer to this crossword clue is the 10 letter word FROLICSOME
I've seen this crossword clue in Financial Times
F
R
O
L
I
C
S
O
M
E
More clues leading to the result FROLICSOME
Buddy explains!

The straight part
We know that "engaged in pranks" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case engaged in pranks = frolicsome.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.
Crossword Answer definitions
FROLICSOME adjective- Characterised or marked by frolicking; playful.