Form of Buddhism (3)
I believe the answer is:
zen
'form of buddhism' is the definition.
(Zen is a school of Buddhism)
This is all the clue.
(Other definitions for zen that I've seen before include "Branch of Buddhism" , "Form of Buddhism stressing meditation" , "Form of Buddhism that says enlightenment comes through meditation" , "Japanese Buddhism" , "Dibdin detective; Jap. Buddhism" .)