A volcanic crater (7)
I believe the answer is:
caldera
'a volcanic crater' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for caldera that I've seen before include "Basin-shaped crater at top of volcano" , "Large volcanic crater - race lad (anag)" , "Result of eruption" , "Big hole in rock" , "Large volcanic crater -- lead car (anag)" .)