Hurry out of Athens! (6)
I believe the answer is:
hasten
'hurry' is the definition.
('hasten' can be a synonym of 'hurry')
'out of athens' is the wordplay.
'out of' is an anagram indicator.
'athens' with letters rearranged gives 'HASTEN'.
(Other definitions for hasten that I've seen before include "Act or move fast" , "Hurry along" , "Hurry up in old-fashioned way" , "race? - with 26a" , "Speed up" .)