Characteristic of old Grecian and yes, so cryptic! (8)
I believe the answer is:
odyssean
'characteristic of old grecian' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'and yes so cryptic' is the wordplay.
'cryptic' indicates anagramming the letters (a cryptic or obscure order of the letters).
'and'+'yes'+'so'='andyesso'
'andyesso' with letters rearranged gives 'ODYSSEAN'.
Can you help me to learn more?
(Other definitions for odyssean that I've seen before include "epic journey" , "Like years of wandering" , "Like travels" , "about epic poem" , "trip involving vessel?" .)