Dead Roman transformed: Greek hero to her rescue (9)
I believe the answer is:
andromeda
'greek hero to her rescue' is the definition.
(Andromeda was rescued by Perseus)
'dead roman transformed' is the wordplay.
'transformed' indicates anagramming the letters.
'dead'+'roman'='deadroman'
'deadroman' anagrammed gives 'ANDROMEDA'.
(Other definitions for andromeda that I've seen before include "Legendary beauty" , "Constellation; daughter of Cassiopeia" , "princess barely chained to rock" , "Greek maid seen in Milan" , "Pattern of stars" .)