Dead Roman exchanged for wife of Perseus (9)
I believe the answer is:
andromeda
'wife of perseus' is the definition.
(I've seen this in another clue)
'dead roman exchanged' is the wordplay.
'exchanged' indicates anagramming the letters.
'dead'+'roman'='deadroman'
'deadroman' with letters rearranged gives 'ANDROMEDA'.
'for' acts as a link.
(Other definitions for andromeda that I've seen before include "Pattern of stars" , "Once on the rocks" , "Damsel in distress" , "Ethiopian princess" , "Object in 21 [SPACE]" .)