Capital of Azerbaijan (4)
I believe the answer is:
baku
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">capital of azerbaijan</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for baku that I've seen before include "Capital of Azerbaijan on shore of Caspian Sea" , "Capital city of Azerbaijan" , "Azerbaijan's capital" , "Caspian Sea port" .)