The most common and most likely answer to this crossword clue is the 7 letter word LORELEI
I've seen this crossword clue in The Times
L
O
R
E
L
E
I
More clues leading to the result LORELEI
- Legend of river and lake that is put back beside other legends
- Siren of traditional stories on the French island
- German rock singer teaching the French one
- Dangerous creature from Transylvania's ready to follow traditions
- Germanic siren featuring in folklore leitmotif
- Some explore, leisurely, a fabulous Rhine feature
- Femme fatale lovelier, not very hideous
- Femme fatale that is turning up in support of good-for-nothing
- Folklore leitmotif? To some extent perhaps she is
- Charmer is lovelier, not very unreliable
Buddy explains!
The straight part
We know that "Dangerous creature" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dangerous creature = lorelei.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.