Tyrannical, sinful monarch crushed (9)
I believe the answer is:
imperious
'tyrannical' is the definition.
(thesaurus)
'sinful monarch crushed' is the wordplay.
I cannot really see how this works, but
'monarch' could be 'er' (abbreviation for Elizabeth Regina, British Queen) and 'er' is found in the answer.
The remaining letters 'impious' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for imperious that I've seen before include "Bossy" , "Arrogant, domineering" , "high-handed" , "Haughty - domineering" .)