Related order for lever (7)
I believe the answer is:
treadle
'lever' is the definition.
(treadle is a kind of lever)
'related order' is the wordplay.
'order' indicates anagramming the letters.
'related' anagrammed gives 'TREADLE'.
'for' acts as a link.
(Other definitions for treadle that I've seen before include "Rocker in a factory" , "Foot lever giving power" , "Pedal operating machine" , "Machine foot-lever" , "machine operator" .)