Rudder bar implement for breaking up soil (6)
I believe the answer is:
tiller
'rudder' is the definition.
(thesaurus)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for tiller that I've seen before include "Boat's steering handle" , "steering contraption" , "Lever to turn the rudder on a boat" , "Handle for turning rudder" , "Boat's steering arm" .)