The chief port of Spain (9)
I believe the answer is:
barcelona
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">the chief port of spain</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 barcelona that I've seen before include "Chief port of Spain" , "Span. City" , "Largest Spanish port" , "Spain's second largest city" , "City and province of Catalonia in NE Spain" .)