Galley mark (4)
I believe the answer is:
stet
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">galley mark</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 stet that I've seen before include "Print as is, don't alter spelling" , "Let it stand (editing mark)" , "Don't alter, let spelling stand" , "Word to cancel change" , "cancel amendment" .)