I note holy man is longing to be laughing (2,8)
I believe the answer is:
'be laughing' is the definition.
I don't know anything about this answer so I can't tell whether this works.
'i note holy man is longing' is the wordplay.
'note' becomes 'n' (abbreviation).
'holy man' becomes 'st' (abbreviation for saint).
'is longing' becomes 'itches' (I can't justify this - if you can you should give a lot more credence to this answer).
'to' is the link.
Can you help me to learn more?
(Other definitions for in stitches that I've seen before include "Following a visit to the theatre one may be" , "Laughing a lot" , "Helpless with laughter" , "much affected by comedy?" , "as one may be on leaving the theatre?" .)