Rigid bars pivoted about a fulcrum (6)
I believe the answer is:
levers
'rigid bars pivoted about a fulcrum' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for levers that I've seen before include "They are pivoted on fulcrums" , "Bars for lifting" , "Prises, jimmies" , "Rigid bars pivoted about a fulcrum" , "Prising bars" .)