Love of cruelty in the modern era is encapsulated by Stalin and Mao primarily (6)
I believe the answer is:
sadism
'love of cruelty' is the definition.
(I've seen this in another clue)
'modern era is encapsulated by stalin and mao primarily' is the wordplay.
'modern era' becomes 'dis' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'is encapsulated by' indicates putting letters inside (I've seen this in other clues).
'primarily' indicates taking the first letters.
The initial letters of 'stalin and mao' is 'sam'.
'dis' inserted inside 'sam' is 'SADISM'.
'in the' acts as a link.
Can you help me to learn more?
(Other definitions for sadism that I've seen before include "Cruel behaviour" , "Enjoyment taken in inflicting pain or cruelty" , "Sexual pleasure from hurting others" , "Dim ass (anag)" , "Delight taken in cruelty" .)