Performer's nervousness (5,6)
I believe the answer is:
stage fright
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">performer's nervousness</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for stage fright that I've seen before include "Actor's fear" , "Pre-performance nerves" , "attack of nerves" , "Performer's nervousness" , "state of nerves" .)