Ground-rent depression? (6)

I believe the answer is:

crater

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'depression?' is the definition.
(crater is a kind of depression)

I can't explain the rest of the clue.

(Other definitions for crater that I've seen before include "Bowl-shaped cavity as on volcano peak" , "Hole formed by impact or explosion" , "Hole of volcano or bomb" , "Great hole as on top of volcano" , "Fissure in the earth's crust" .)

I've seen this clue in The Globe and Mail.

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