Fragmentary report of dinner organised by UN? (9)

I believe the answer is:
piecemeal
'fragmentary' is the definition.
(thesaurus)
'report of dinner organised by un?' is the wordplay.
I cannot really understand how this works, but
'dinner' could be 'meal' (dinner is a meal) and 'meal' is found within the answer.
The remaining letters 'piece' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for piecemeal that I've seen before include "a little at a time" , "Bit by bit; unsystematic" , "by degrees" , "Unsystematically" , "Gradually, little by little" .)
