Step on the French pedal (7)
I believe the answer is:
treadle
'pedal' is the definition.
('treadle' can be a synonym of 'pedal')
'step on the french' is the wordplay.
'step' becomes 'tread' ('tread' can be a synonym of 'step'**).
'on' means one lot of letters go next to another.
'the french' becomes 'le'.
'tread'+'le'='TREADLE'
(Other definitions for treadle that I've seen before include "Foot-pedal" , "Foot lever working machine" , "Rocking lever operated by foot" , "(Machine's) foot-control" , "machine operator" .)