The most common and most likely answer to this crossword clue is the 9 letter word HORSEPLAY
I've seen this crossword clue in Independent
H
O
R
S
E
P
L
A
Y
More clues leading to the result HORSEPLAY
- Antics succeeded in transforming hero Macbeth?
- Fooling around in Equus perhaps?
- Shenanigans, as poser rolls around with first of ladies in the grass
- Tomfoolery from Arab given latitude?
- Shaffer’s main work decried as “a bit of fun”
- Knockabout versions of Equus ?
- Finally peer into a spyhole sneakily, observing fun and games
- Spare holy ground for boisterous activity
- Acting boisterously in ‘Equus’?
- Hop around layers, it's a caper
Buddy explains!

The straight part
We know that "Fooling around" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fooling around = horseplay.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 HORSEPLAY mean?
HORSEPLAY noun- Rough or rowdy play that can often result in unintentional physical harm.
- To engage in horseplay.