System of weights (4)
'system of weights' is the definition.
(troy is a kind of system of weights)
This is the entire clue.
(Other definitions for troy that I've seen before include "Weight system - old city" , "Iliad siege city" , "System of weights introduced by French" , "City destroyed" , "Ancient beseiged city" .)
'system of weights' is the definition.
(avoirdupois is a kind of system of weights)
This is the entire clue.
(Other definitions for avoirdupois that I've seen before include "sort of weight" , "Imperial system of weights - unwanted fat" , "Pounds/ounces system of weights" , "Non-metric system of weights" .)