The most common and most likely answer to this crossword clue is the 8 letter word HILARITY
I've seen this crossword clue in Financial Times
H
I
L
A
R
I
T
Y
More clues leading to the result HILARITY
- Absence of gravity, or term describing it
- The very thing dividing boy and girl is splitting sides?
- It's introduced before end of term merriment
- . Thing not specified in legal term offering great amusement
- Term at school about it produces merriment
- Merriment? Term restricts it
- Fun having vermouth during Oxford term
- Clinton gets around it with glee
- Amusement caused by it during Spring term at Oxford
- Laughter or a term embracing it
Buddy explains!

The straight part
We know that "merriment" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case merriment = hilarity.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 HILARITY mean?
HILARITY noun- A great amount of amusement, usually accompanied by laughter.
- Something that induces laughter.