Turn again to the river (3)
I believe the answer is:
ure
'the river' is the definition.
(I have seen 'River of Wensleydale ' mean 'ure' so perhaps 'river' could also mean 'ure')
'turn again' is the wordplay.
'turn' becomes 'u' (a 'U-turn' is a kind of turn).
'again' becomes 're'.
'u'+'re'='URE'
'to' is the link.
(Other definitions for ure that I've seen before include "Midge --, singer" , "River of N. Yorkshire" , "Wensleydale river" , "River at Ripon" , "Ripon's river" .)