Laughing one’s head off bothering this insect (2,8)
I believe the answer is:
in stitches
'laughing one's head off' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'bothering this insect' is the wordplay.
'bothering' indicates an anagram.
'this'+'insect'='thisinsect'
'thisinsect' anagrammed gives 'IN STITCHES'.
Can you help me to learn more?
(Other definitions for in stitches that I've seen before include "extremely amused" , "Laughing uncontrollably" , "After an operation" , "as one may be on leaving the theatre?" , "Helpless with laughter" .)