Insertion symbol (5)
I believe the answer is:
caret
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">insertion symbol</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 caret that I've seen before include "Particular mark" , "this reveals something missing" , "It shows what to put in" , "Text mark indicating insertion" , "Upward arrow mark" .)