Big ravine (5)
I believe the answer is:
gorge
'big ravine' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for gorge that I've seen before include "something close to Cheddar?" , "Gobble" , "Make a pig of oneself" , "Devour" , "Chasm; overeat" .)