Like heartless queen's lascivious look (4)
I believe the answer is:
leer
'lascivious look' is the definition.
(I've seen this before)
'like heartless queen's' is the wordplay.
'heartless' means to remove the middle letters.
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'like' with its middle removed is 'le'.
'le'+'er'='LEER'
(Other definitions for leer that I've seen before include "Look lecherously" , "Give lascivious look" , "Look lasciviously at" , "Lecherous look" , "Suggestive or sneering grin" .)