Tower city (4)
I believe the answer is:
pisa
'tower city' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for pisa that I've seen before include "City in Tuscany" , "There's a marked inclination here" , "Tuscan city" , "City on the River Arno" , "City with listed building" .)