Dutch city (6)
(Another definition for leiden that I've seen is " Dutch city with old university".)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">dutch 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 arnhem that I've seen before include "place noted for fighting" , "Netherlands scene of 1944 battle" , "Site of 1944 battle" , "Dutch city" , "Location of battle" .)