Ogle the French monarch (4)
I believe the answer is:
leer
'ogle' is the definition.
(I've seen this before)
'the french monarch' is the wordplay.
'the french' becomes 'le' ('the' in French).
'monarch' becomes 'ER' (abbreviation for Elizabeth Regina, British Queen).
'le'+'er'='LEER'
(Other definitions for leer that I've seen before include "Look suggestively" , "Lewd look" , "Lascivious gaze" , "Gaze lasciviously at" , "Stare suggestively" .)