Form of Buddhism, nothing more, for Greek philosopher (4)
I believe the answer is:
zeno
'greek philosopher' is the definition.
(I've seen this before)
'form of buddhism nothing more' is the wordplay.
'form of buddhism' becomes 'zen' (I've seen this before).
'nothing more' becomes 'o' (resembles 0).
'zen'+'o'='ZENO'
'for' acts as a link.
(Other definitions for zeno that I've seen before include "Eleatic philosopher" , "Gr. philosopher of Elea" , "Stoical leader" , "Philosopher's" , "Greek philosopher of paradox fame" .)