Leaning Tower city (4)
I believe the answer is:
pisa
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">leaning tower city</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(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" .)