Seven stars break ground (6)
I believe the answer is:
plough
I believe this is a double definition.
'seven stars' is the first definition.
(the Plough is a constellation of seven stars)
'break ground' is the second definition.
(to plough is to break up ground)
(Other definitions for plough that I've seen before include "Agricultural implement" , "Furrow cutter" , "Make furrows" , "Cultivate" , "Farm tool for cutting furrows" .)