Falsify, counterfeit (5)
I believe the answer is:
forge
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">falsify</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >'<span class="explanation-format__original">counterfeit</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ ></span>
(Other definitions for forge that I've seen before include "Shape by heating and hammering, as smith does" , "Smith's workplace" , "Smithy; falsify" , "Smith's workshop" , "Create; counterfeit" .)