Thin sword (6)
I believe the answer is:
rapier
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">thin sword</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 rapier that I've seen before include "A small spring flower" , "Straight sword with narrow blade" , "Fine-bladed sword" , "Thrusting weapon" , "Straight narrow sword with two edges" .)