Rhine siren (7)
I believe the answer is:
lorelei
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rhine siren</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for lorelei that I've seen before include "Dangerous female" , "A dangerously attractive lady" , "Fateful singer" , "Fatal attraction" , "voice to die for" .)