Cracking up, post-op? (2,8)
I believe the answer is:
in stitches
'cracking up' is the definition.
(I've seen this in another clue)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for in stitches that I've seen before include "Helpless with laughter" , "Laughing a lot" , "Following a visit to the theatre one may be" , "Laughing uncontrollably" , "After an operation" .)