Cultural Revolution's end, in principle (6)
I believe the answer is:
ethnic
'cultural' is the definition.
(I've seen this before)
'revolution's end in principle' is the wordplay.
'revolution's end' becomes 'n' (I can't explain this - if you can you should give a lot more credence to this answer).
'in' means one lot of letters goes inside another.
'principle' becomes 'ethic' (ethic is a kind of principle).
'n' placed inside 'ethic' is 'ETHNIC'.
Can you help me to learn more?
(Other definitions for ethnic that I've seen before include "Of nations and races" , "Relating to a cultural grouping" , "To do with race or nationality" , "Denoting origin by descent" , "Relating to races" .)