Emphatic men must change accusation (11)
I believe the answer is:
impeachment
'accusation' is the definition.
(impeachment is a process of making an accusation)
'emphatic men must change' is the wordplay.
'must change' indicates anagramming the letters (I've seen this in other clues).
'emphatic'+'men'='emphaticmen'
'emphaticmen' with letters rearranged gives 'IMPEACHMENT'.
(Other definitions for impeachment that I've seen before include "Legal process of removal from office" , "charge" .)