Be incorrect (3)
I believe the answer is:
err
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">be incorrect</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for err that I've seen before include "'to... is human,to forgive divine'" , "Make mistakes" , "Make a wrong move" , "Make mistake in Canberra" , "Leave the straight and narrow" .)