Furniture wheel (6)
I believe the answer is:
caster
'furniture wheel' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for caster that I've seen before include "Crates with kind of fine sugar" , "Small swivelling wheel on furniture" , "One who throws something" , "Founder; type of 12 Ac" , "Swivelling wheel (E, not O)" .)