The most common and most likely answer to this crossword clue is the 7 plus 8 letter word HOMERIC LAUGHTER
I've seen this crossword clue in The Times
H
O
M
E
R
I
C
L
A
U
G
H
T
E
R
Buddy explains!
The straight part
We know that "hysterics" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case hysterics = homeric laughter.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.