Run off waste (6)
I believe the answer is:
desert
I believe this is a double definition.
'run off' is the first definition.
(thesaurus)
'waste' is the second definition.
('desert' can be a synonym of 'waste')
(Other definitions for desert that I've seen before include "Abandon in arid area" , "Abandon; dry region" , "Waterless area of land" , "sands" , "part of Africa?" .)