Cases for Greek philosopher? Not so! (6)
I believe the answer is:
crates
'cases' is the definition.
(crating is a kind of casing)
'greek philosopher? not so' is the wordplay.
'greek philosopher?' becomes 'socrates' (I've seen this before).
'not' is a deletion indicator.
'socrates' with 'so' taken out is 'CRATES'.
'for' acts as a link.
(Other definitions for crates that I've seen before include "Packing cases" , "Boxes for shipping goods" , "Jalopies" , "Rough wooden boxes" .)