Hole in the ground (6)
I believe the answer is:
crater
'hole in the ground' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for crater that I've seen before include "big hole" , "Bowl-shaped cavity as on volcano peak" , "Hole formed by impact or explosion" , "Fissure in the earth's crust" , "Volcano's mouth" .)