Hitman is re-entered in these classical games (8)
I believe the answer is:
isthmian
'games' is the definition.
(I have seen 'old games' mean 'isthmian' so perhaps 'games' could also mean 'isthmian')
'hitman is re-entered in these classical' is the wordplay.
'hitman is' anagrams to 'ISTHMIAN'.
Though, I'm not sure how this is indicated.
Can you help me to learn more?
(Other definitions for isthmian that I've seen before include "Relating to a neck of land - mini hats (anag)" , "Ian Smith? (Anag)" , "old games" , "in the games in Greece" , "person from Panama, say" .)