Show off at the gym
I believe the answer is:
flex
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">show off at the gym</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for flex that I've seen before include "Bend; electric lead" , "Insulated wire cable" , "Bendable cord" , "Bend (muscle?)" , "Electric wire" .)