Perform, as if in a play (5)
I believe the answer is:
enact
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">perform as if in a play</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 enact that I've seen before include "Authorize" , "Present" , "Establish by statute" , "Decree" , "Make (a bill) law" .)