To Jason she was a real charmer (5)
I believe the answer is:
medea
'charmer' is the definition.
(thesaurus)
'to jason she was a real' is the wordplay.
I cannot really see how this works, but
'she' could be 'ede' and 'ede' is found within the answer.
'a' is found in the answer.
A single letter 'm' remains which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for medea that I've seen before include "Mythical enchantress" , "In Greek myth, Jason's wife who killed their children in jealous rage" , "Mythological Greek princess" , "fabulous princess" , "Tragedy by Euripides" .)