Ancient city, partly destroyed (4)
I believe the answer is:
troy
'ancient city' is the definition.
(I've seen this before)
'partly destroyed' is the wordplay.
'partly' indicates a hidden word.
'TROY' can be found hidden inside 'destroyed'.
(Other definitions for troy that I've seen before include "Besieged city which fell to Wooden Horse" , "Ancient city; type of weight" , "System of weights introduced by French" , "part of Asia Minor" , "Ancient city besieged to free beautiful Helen" .)