Made mistakes (5)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">made mistakes</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for erred that I've seen before include "Was mistaken" , "Went astray" , "Strayed from the straight and narrow" , "Made mistakes" , "Made mistake, was incorrect" .)
(Another definition for floundered that I've seen is " Was out of one's depth".)