Sediment in which dogs run wild (7)
I believe the answer is:
grounds
'sediment' is the definition.
(as in coffee grounds)
'dogs run wild' is the wordplay.
'wild' is an anagram indicator.
'dogs'+'run'='dogsrun'
'dogsrun' is an anagram of 'GROUNDS'.
'in which' acts as a link.
(Other definitions for grounds that I've seen before include "Refuses authority to fly" , "reason" , "justification" , "Area of enclosed land around a building" , "they make coffee" .)