K-Pop star's revolutionary spirit (6)
I believe the answer is:
psyche
'spirit' is the definition.
(psyche is a kind of spirit)
'k-pop star's revolutionary' is the wordplay.
'k-pop star' becomes 'psy' (South Korean musician).
'revolutionary' becomes 'che' (Che Guevara the Marxist revolutionary).
'psy'+'che'='PSYCHE'
(Other definitions for psyche that I've seen before include "Individuality" , "Wife of Cupid" , "Human faculty for thought - Cupid's lover" , "Subject of 11 [ODE]" , "Human mind or spirit" .)