Prick (5)
(Other definitions for thorn that I've seen before include "Pointed growth" , "tip of R [ROSE]" , "Something 20 [SHARP]" , "North (anag) -- point" , "eg Prickle on rose" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">prick</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that prick is a more specific form of the action prick)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for sting that I've seen before include "Smart - cheat" , "(Bee) wound" , "piece of deception" , "18, sharp pain" , "fleece?" .)