A physical exercise (5-2)
I believe the answer is:
press-up
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">a physical exercise</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that press-up is a type of arm exercise)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for press-up that I've seen before include "Gymnastic floor exercise" , "Face-to-the-floor exercise" , "Form of arm exercise" , "Keep-fit exercise" , "Arm exercise while lying face down" .)