Reverse management's reshuffle after married man is dismissed (6)
I believe the answer is:
negate
'reverse' is the definition.
(thesaurus)
I don't understand how the remainder of the clue works.
(Other definitions for negate that I've seen before include "Deny the truth of" , "Nullify - deny the existence of" , "Contradict" , "disallow!" , "Cancel; invalidate" .)