Play about conclusion of war in ancient city (4)
I believe the answer is:
troy
'ancient city' is the definition.
(Troy was an ancient city)
'play about conclusion of war' is the wordplay.
'play' becomes 'toy' (synonyms).
'about' means one lot of letters goes inside another.
'conclusion of' says to take the final letters.
The last letter of 'war' is 'r'.
'toy' placed around 'r' is 'TROY'.
'in' acts as a link.
(Other definitions for troy that I've seen before include "Ancient city in Asia Minor" , "Ancient city besieged by the Greeks" , "Priam's city" , "System of weights introduced by French" , "Besieged city which fell to Wooden Horse" .)