Reported tragic king's lecherous look (4)
I believe the answer is:
leer
'lecherous look' is the definition.
(leer can mean a lecherous or suggestive look)
'reported tragic king's' is the wordplay.
'reported' indicates a 'sounds like' (homophone) clue.
'tragic king' becomes 'Lear' (Shakespeare's King Lear).
'lear' sounds like 'LEER'.
(Other definitions for leer that I've seen before include "Ogle, smirk" , "Give lascivious look" , "Stare suggestively" , "Lascivious gaze" , "Gaze lasciviously at" .)