Roughly stuffing tree in crater (7)
I believe the answer is:
caldera
'crater' is the definition.
(I know that Caldera is a type of crater)
'roughly stuffing tree in' is the wordplay.
'roughly' becomes 'ca' (abbreviation for circa).
'stuffing tree' becomes 'alder' (I am not sure about this - if you are sure you should believe this answer much more).
'in' is an insertion indicator.
'ca' enclosing 'alder' is 'CALDERA'.
Can you help me to learn more?
(Other definitions for caldera that I've seen before include "Large volcanic crater - race lad (anag)" , "Big hole in rock" , "Large volcanic crater -- lead car (anag)" , "Basin-shaped crater at top of volcano" , "Result of eruption" .)