Pollute gorge (6)
I believe the answer is:
defile
This clue is a double definition.
'pollute' is the first definition.
(I've seen this before)
'gorge' is the second definition.
(synonyms)
(Other definitions for defile that I've seen before include "passage" , "Pollute, make dirty" , "Create pollution" , "dishonour?" , "Soil" .)