Rotten king: terrible ruler going over outline of speech (7)
I believe the answer is:
knavish
'rotten' is the definition.
Both the answer and definition are adjectives. Perhaps there's an association between them I don't understand?
'king terrible ruler going over outline of speech' is the wordplay.
'king' becomes 'K' (abbreviation for king in chess).
'terrible ruler' becomes 'ivan' (tsar of Russia Ivan the Terrible).
'going over' shows that the letters should be reversed in order.
'outline of' suggests removing the centre (outline refers to the letters on the edges).
'speech' with its centre removed is 'sh'.
'ivan' reversed gives 'navi'.
'k'+'navi'+'sh'='KNAVISH'
Can you help me to learn more?
(Other definitions for knavish that I've seen before include "Dishonest, unscrupulous" , "Rascally" , "Wily" , "Fraudulent" , "like one able to beat ten?" .)