She's a danger to navigation! (7)

I believe the answer is:

lorelei

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'she's' is the definition.

I cannot understand how the remainder of the clue works.

(Other definitions for lorelei that I've seen before include "Rhine Rock where siren lived" , "Rhine rock of siren legend" , "enchantress" , "A dangerously attractive lady" , "voice to die for" .)

I've seen this clue in the Evening Standard.

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