Right to graze cattle in former city once upon a time (9)
I believe the answer is:
pasturage
'right to graze cattle' is the definition.
I can't judge whether this definition defines the answer.
'former city once upon a time' is the wordplay.
'former' becomes 'past' (similar in meaning).
'city once' becomes 'ur' (ancient Sumerian city state).
'upon' says to put letters next to each other.
'a time' becomes 'age' (an age is a period of time).
'past'+'ur'+'age'='PASTURAGE'
'in' is the link.
Can you help me to learn more?
(Other definitions for pasturage that I've seen before include "grazing land" , "Grassland" .)