Marshy ground (6)
I believe the answer is:
morass
'marshy ground' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for morass that I've seen before include "Tract of swampy land" , "Bog; confused situation" , "Area of boggy ground" , "Bog - situation hard to get out of" , "Slough - marsh" .)