She's dangerous, especially to boatmen (7)
I believe the answer is:
lorelei
'she's' is the definition.
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for lorelei that I've seen before include "Legendary siren who lured Rhine boatmen to destruction" , "Fateful singer" , "Rhine Rock where sirens once dwelled" , "Legendary siren luring Rhine boatmen to destruction" , "A Rhine maiden" .)