Prussian lancer
I believe the answer is:
uhlan
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">prussian lancer</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 uhlan that I've seen before include "Prussian lancer" , "Cavalryman" , "Horseman once" .)