Somerset cathedral city (5)
I believe the answer is:
wells
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">somerset cathedral 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 wells that I've seen before include "Somerset cathedral city" , "Oil sources" , "Cathedral city; sci-fi writer" , "What a boring person might produce" , "Author" .)