Alarm the bewitching creature (5)
I believe the answer is:
siren
I believe this clue is a triple definition!
'alarm' is the first definition.
(I know that siren is a type of alarm)
'the bewitching' is the second definition.
(thesaurus)
'creature' is the third definition.
(I know that siren is a type of adult female)
(Other definitions for siren that I've seen before include "Seductress" , "Warning sound" , "Seductive woman" , "Alarm; temptress" , "Warning at sea" .)