Failure; counterfeit (3)
I believe the answer is:
dud
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">failure</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that dud is a type of failure)</span><br/ ><br/ >'<span class="explanation-format__original">counterfeit</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for dud that I've seen before include "Defective" , "'Flop, turkey (3)'" , "Useless, doesn't work - a palindrome" , "Fake -- failure" , "Useless, ineffective" .)