Rose to become immortal (4)
I believe the answer is:
eros
'immortal' is the definition.
(Eros is an example)
'rose to become' is the wordplay.
'to become' indicates an anagram.
'rose' anagrammed gives 'EROS'.
(Other definitions for eros that I've seen before include "divinity" , "Roman god of love, Cupid" , "asteroid four hundred and thirty three" , "I'm in a circus in London" , "Cupid's Greek alternative" .)