Work muddled dean with king (5)
I believe the answer is:
knead
'work' is the definition.
('knead' can be a synonym of 'work')
'muddled dean with king' is the wordplay.
'muddled' indicates anagramming the letters.
'with' is a charade indicator (letters next to each other).
'king' becomes 'k' (**).
'dean' with letters rearranged gives 'nead'.
'nead' put after 'k' is 'KNEAD'.
(Other definitions for knead that I've seen before include "Work (dough) into mass" , "Pummel dough" , "Somehow work in" , "Work (dough/clay)" , "Massage - naked (anag)" .)