Thus an Athenian cross with Olympic city? (5)
I believe the answer is:
sochi
'olympic city?' is the definition.
I know nothing about this answer so I cannot tell whether this works.
'thus an athenian cross' is the wordplay.
'thus' becomes 'so' (synonyms).
'an athenian cross' becomes 'chi' (I can't explain this - if you can you should give a lot more credence to this answer).
'so'+'chi'='SOCHI'
'with' acts as a link.
Can you help me to learn more?
(Another definition for sochi that I've seen is " Winter Olympics venue".)