Ask too much of English king in public (9)
I believe the answer is:
overexert
'ask too much' is the definition.
I can't judge whether this definition defines the answer.
'english king in public' is the wordplay.
'english' becomes 'E' (abbreviation).
'king' becomes 'rex' ('king' in Latin).
'in' indicates putting letters inside.
'public' becomes 'overt' (both can mean well-known or unconcealed).
'e'+'rex'='erex'
'erex' inserted into 'overt' is 'OVEREXERT'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for overexert that I've seen before include "exercise unduly?" , "strain" , "use too much" , "work too hard" , "Make too much effort" .)