Time to chase villain crossing large volcanic crater (7)
I believe the answer is:
caldera
'volcanic crater' is the definition.
(I've seen this before)
'time to chase villain crossing large' is the wordplay.
'time' becomes 'era' (era is a kind of time).
'to chase' means one lot of letters go next to another.
'villain' becomes 'cad' (cad can mean a nasty person).
'crossing' means one lot of letters goes inside another.
'large' becomes 'L' (eg in clothes sizes).
'cad' placed around 'l' is 'cald'.
'era' after 'cald' is 'CALDERA'.
(Other definitions for caldera that I've seen before include "Result of eruption" , "Large volcanic crater -- lead car (anag)" , "Basin-shaped crater at top of volcano" , "Large volcanic crater - race lad (anag)" , "Big hole in rock" .)