Rigid bar pivoting about a fulcrum (5)
I believe the answer is:
lever
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">rigid bar pivoting about a fulcrum</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 lever that I've seen before include "Revel in moving bar" , "Crowbar" , "Lifting bar pivoted on a fulcrum" , "Exert pressure" , "Kind of bar for prising or lifting" .)