Where Paris took Helen (4)
I believe the answer is:
'where paris took helen' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for troy that I've seen before include "City besieged by Greeks to rescue Helen" , "The war for it, Homer" , "Ancient city; type of weight" , "Ancient city besieged by the Greeks" , "Iliad siege city" .)