Cause sediment (7)
I believe the answer is:
grounds
I believe this is a double definition.
'cause' is the first definition.
(I know that cause can be written as grounds)
'sediment' is the second definition.
(as in coffee grounds)
(Other definitions for grounds that I've seen before include "Refuses authority to fly" , "they make coffee" , "reason" , "Dregs" , "enclosure around house" .)