The most common and most likely answer to this crossword clue is the 9 letter word TEMPTRESS
I've seen this crossword clue in The Times
T
E
M
P
T
R
E
S
S
More clues leading to the result TEMPTRESS
- Mostly futile cracking lock — siren results
- Siren: one working without security lock
- Femme fatale sovereign arrests time after time
- Flirt with casual girl around the end of December
- Streets PM wanders to find lady of a seductive bent
- Siren time and time again interrupting tsarina?
- Workers dressing very Gallic femme fatale
- Stand-in gets lock for siren
- Siren seen by casual worker at lock
- Attractive woman, interim staff member with long hair
Buddy explains!

The straight part
We know that "siren" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case siren = temptress.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.
What does TEMPTRESS mean?
TEMPTRESS noun- An alluring woman who seduces or exploits men.
- A woman considered sexually attractive by men.