Swiss city on the Rhine (5)
(Other definitions for basle that I've seen before include "Swiss city and canton" , "Canton of NW Switzerland" , "Swiss city for sable?" , "Canton of N W Switzerland" , "European city" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">swiss city on the rhine</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for basel that I've seen before include "In European city" , "Swiss city" , "City of Switzerland" .)