For hire, including river and stream (7)
I believe the answer is:
torrent
'stream' is the definition.
(I know that torrent is a type of stream)
'for hire including river' is the wordplay.
'for' becomes 'to' (eg both can mean 'in the opinion of').
'hire' becomes 'rent' (synonyms).
'including' means one lot of letters goes inside another.
'river' becomes 'r' (abbreviation for river).
'rent' placed around 'r' is 'rrent'.
'to'+'rrent'='TORRENT'
'and' is the link.
(Other definitions for torrent that I've seen before include "Fast-moving stream" , "Turbulent, swift-flowing stream" , "Overwhelming flow" , "Stream in spate" , "Great stream" .)