Bluebeard occasionally has lascivious look (4)
I believe the answer is:
leer
'lascivious look' is the definition.
(I've seen this before)
'bluebeard occasionally' is the wordplay.
'occasionally' indicates alternate letters.
The alternate letters of 'bluebeard' are 'LEER'.
'has' acts as a link.
(Other definitions for leer that I've seen before include "Look lecherously" , "Lascivious gaze" , "Give lascivious look" , "unpleasant look" , "Ogle, smirk" .)