US city showing elegance in the past (7)
I believe the answer is:
Here is my best explanation:
'us city' is the definition.
(I've seen this before)
'elegance in the past' is the subsidiary indication.
'elegance' becomes 'chic' (chic is a kind of elegance).
'in the past' becomes 'ago' ('ago' can be a synonym of 'in the past').
'showing' is the link.
(Other definitions for chicago that I've seen before include "A windy place", "3 city in the US", "Type of bridge", "The Windy City", "Windy City of USA", "US city - musical featuring All That Jazz", "A Windy City in Illinois", "Port on Lake Michigan", "Musical (in Illinois?)" and "Al Capone's city".)