Singing nymph of the Rhine (7)
I believe the answer is:
lorelei
'singing nymph of the rhine' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for lorelei that I've seen before include "Legendary siren and rock in the R Rhine" , "Bloody singer" , "Fascinating women" , "Rhine Rock where sirens once dwelled" , "Siren of German legend who lured boatmen in the Rhine to destruction" .)