High ground cleft by rushing stream? (7)
I believe the answer is:
'rushing stream?' is the definition.
(I've seen this before)
'high ground cleft by' is the wordplay.
'high ground' becomes 'tor'.
'cleft' becomes 'rent' (synonyms).
'by' means one lot of letters go next to another.
(Other definitions for torrent that I've seen before include "Inundation" , "Violently fast stream of water" , "Raging flow" , "Fast-moving stream" , "Turbulent, swift-flowing stream" .)