The man dismissed from Ashes is a fool (3)
I believe the answer is:
ass
'a fool' is the definition.
(ass is a kind of fool)
'the man dismissed from ashes' is the wordplay.
'the man' becomes 'he'.
'dismissed from' indicates named letters should be taken away.
'ashes' with 'he' taken away is 'ASS'.
'is' is the link.
(Other definitions for ass that I've seen before include "Long-eared animal" , "Quadruped; fool" , "Democratic mascot" , "Clinton's behind" , "Hardy and sure-footed animal" .)