Ground rent depression? (6)
I believe the answer is:
crater
This might be a double definition.
'ground rent' is the first definition.
The answer and definition can be both natural objects as well as being singular nouns.
Perhaps you can see a link between them that I don't see?
'depression?' is the second definition.
(I know that crater is a type of depression)
Can you help me to learn more?
(Other definitions for crater that I've seen before include "Bowl-shaped cavity, in a volcano say" , "Lunar surface dent" , "Volcano's mouth" , "Geological depression" , "Hole of volcano or bomb" .)