The most common and most likely answer to this crossword clue is the 7 letter word CORPSED
I've seen this crossword clue in The Guardian
C
O
R
P
S
E
D
More clues leading to the result CORPSED
Buddy explains!

The straight part
We know that "collapsed in laughter" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case collapsed in laughter = corpsed.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 CORPSED mean?
CORPSED verb- (of an actor) To lose control during a performance and laugh uncontrollably.