King and Ace encapsulating power and fate (5)
I believe the answer is:
karma
'fate' is the definition.
(I know that karma is a type of fate)
'king and ace encapsulating power' is the wordplay.
'king' becomes 'K' (abbreviation for king in chess).
'and' says to put letters next to each other.
'ace' becomes 'a'.
'encapsulating' indicates putting letters inside (I've seen this in other clues).
'power' becomes 'arm' (arm can mean power or strength).
'k'+'a'='ka'
'ka' placed around 'arm' is 'KARMA'.
'and' acts as a link.
(Other definitions for karma that I've seen before include "Destiny, of Buddhism and Hinduism" , "In Buddhism, the sum of a person's existence - determines future" , "Fate; result of one's past deeds" , "(In Hinduism or Buddhism) this decides one's fate in a future existence" , "Actions determining destiny" .)