Hitman is running from a part of Greece (8)
I believe the answer is:
isthmian
'from a part of greece' is the definition.
(from the Isthmus of Corinth in Greece)
'hitman is running' is the wordplay.
'running' is an anagram indicator.
'hitman'+'is'='hitmanis'
'hitmanis' is an anagram of 'ISTHMIAN'.
(Other definitions for isthmian that I've seen before include "Relating to a neck of land - mini hats (anag)" , "person from Panama, say" , "old games" , "in the games in Greece" , "Ian Smith? (Anag)" .)