Earth reduced to powder (6)
I believe the answer is:
ground
I believe this is a double definition.
'earth' is the first definition.
(I know that earth can be written as ground)
'reduced to powder' is the second definition.
(I've seen this before)
(Other definitions for ground that I've seen before include "Earth; stop from flying" , "Arena" , "Powdered; land" , "reduced to dust" , "Solid part of the earth's surface" .)