Hill split by flood (7)
I believe the answer is:
'flood' is the definition.
(a torrent is a large amount of water)
'hill split by' is the wordplay.
'hill' becomes 'tor' (tor is a kind of hill).
'split' becomes 'rent' (past tense of 'rend' meaning to split).
'by' is a charade indicator (letters next to each other).
(Other definitions for torrent that I've seen before include "fast-moving flow" , "Fast-moving stream" , "Strong stream" , "A rushing stream of water" , "Overwhelming deluge" .)