Greek philosopher known for a paradox (4)
I believe the answer is:
zeno
'greek philosopher known for a paradox' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for zeno that I've seen before include "Greek philosopher of paradox fame" , "Greek philosopher of Elea (paradoxes)" , "Gr. philosopher of Elea" , "Stoical leader" , "Old mathematician" .)