Residential district on a city's outskirts (8)
I believe the answer is:
suburbia
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">residential district on a city's outskirts</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for suburbia that I've seen before include "Outer city regions" , "Residential districts on the outskirts of a city" , "Residential district on a city's outskirts" , "Pet Shop Boys song" , "Residential area away from city centre" .)