Leaning Tower city (4)
I believe the answer is:
pisa
'leaning tower city' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for pisa that I've seen before include "Location of leaning tower" , "Site of the famous leaning tower" , "much-visited city" , "listed building site" , "City on the River Arno" .)