Weighing machines (6)
I believe the answer is:
scales
'weighing machines' is the definition.
('scale' can be a synonym of 'weighing machine')
This is the entire clue.
(Other definitions for scales that I've seen before include "Removes plaque" , "a number of small plates" , "Climbs the weight measuring device" , "Measuring instrument for weighing" , "Climbs - balances" .)