Strauss heroine's death coming up after song (7)
I believe the answer is:
ariadne
'strauss heroine's' is the definition.
(I've seen this in another clue)
'death coming up after song' is the wordplay.
'death' becomes 'end' (synonyms).
'coming up' says the letters should be written in reverse (in a down clue, letters go up).
'after' says to put letters next to each other.
'song' becomes 'aria' (piece of music in an opera).
'end' reversed gives 'dne'.
'dne' put after 'aria' is 'ARIADNE'.
(Other definitions for ariadne that I've seen before include "heroine of labyrinth" , "Aid near (anag) - Theseus's girl" , "Mythological Greek" , "Female in labyrinth" , "Straussian heroine" .)