One has agents sorting out party mess (9)
I believe the answer is:
spymaster
'one has agents sorting' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.
'out party mess' is the wordplay.
'out' indicates anagramming the letters.
'party'+'mess'='partymess'
'partymess' with letters rearranged gives 'SPYMASTER'.
Can you help me to learn more?
(Other definitions for spymaster that I've seen before include "Eg, head of MI6" , "Bond's M, perhaps" , "007's boss?" , "Someone who directs clandestine intelligence activities" , "Eg, Bond's M" .)