Bog or marsh (5)
I believe the answer is:
swamp
I believe this clue is a double definition.
'bog' is the first definition.
(I've seen this before)
'marsh' is the second definition.
(I've seen this before)
(Other definitions for swamp that I've seen before include "Boggy ground" , "Bog, marsh" , "Slough" , "Waterlogged ground" , "marshy tract" .)