Duffer (5)
I believe the answer is:
dunce
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">duffer</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 dunce that I've seen before include "School fool" , "Unkind word for slow learner" , "Halfwit" , "Dull chap" , "Term of ridicule applied to followers of John Duns Scotus" .)