Buddhist discipline (3)
I believe the answer is:
zen
'buddhist discipline' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for zen that I've seen before include "Japanese Buddhism" , "Dibdin detective; Jap. Buddhism" , "Branch of Buddhism" , "Form of Buddhism, emphasises meditation" , "Form of Buddhism that says enlightenment comes through meditation" .)