Hamburg's river (4)
I believe the answer is:
elbe
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hamburg's river</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 elbe that I've seen before include "German banker" , "Flower" , "River of Germany" , "Dresden/Hamburg river" , "European river" .)