Priam's domain (4)
I believe the answer is:
'priam's domain' 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 "Ancient city in Asia Minor" , "Weight system - old city" , "Iliad siege city" , "Ancient city besieged to free beautiful Helen" , "System of weights introduced by French" .)