Forbidden City's flattened structure (6)
I believe the answer is:
tabula
'flattened structure' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'forbidden city's' is the wordplay.
'forbidden' becomes 'tabu' (synonyms).
'city' becomes 'LA' (Los Angeles).
'tabu'+'la'='TABULA'
Can you help me to learn more?
(Other definitions for tabula that I've seen before include "- rasa means a clean slate in Latin" , "... rasa, a clean slate for a fresh start" .)