Jouster's weapon (5)
I believe the answer is:
lance
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">jouster's weapon</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for lance that I've seen before include "Spear carried by mounted soldier" , "Horseman's long weapon" , "Boy - prick (a boil)" , "Pierce (a boil)" , "Surgical knife" .)