Your extremely evil master’s twisted jesting (8)
I believe the answer is:
drollery
'jesting' is the definition.
(both can mean joking)
'your extremely evil master's twisted' is the wordplay.
'your' becomes 'yr'.
'extremely' means to remove the middle letters (only the extremes of the word are used).
'master' becomes 'lord' (synonyms).
'twisted' is a reversal indicator.
'evil' with its centre removed is 'el'.
'yr'+'el'+'lord'='yrellord'
'yrellord' in reverse letter order is 'DROLLERY'.
(Other definitions for drollery that I've seen before include "Jesting" , "Jest; buffoonery" , "jokes" , "Comical quality" , "comedy" .)