Irate Mod disturbed negotiator (8)
I believe the answer is:
mediator
'negotiator' is the definition.
(mediator is a kind of negotiator)
'irate mod disturbed' is the wordplay.
'disturbed' is an anagram indicator (the order of letters is disturbed).
'irate'+'mod'='iratemod'
'iratemod' with letters rearranged gives 'MEDIATOR'.
(Other definitions for mediator that I've seen before include "Kind of arbitrator - one to admire" , "peacemaker" , "One intervening to settle a dispute" , "An honest broker" , "One seeking to reconcile opponents" .)