River forms new line (4)
I believe the answer is:
nile
'river' is the definition.
(I know that Nile is a river)
'new line' is the wordplay.
'new' is an anagram indicator.
'line' anagrammed gives 'NILE'.
'forms' is the link.
(Other definitions for nile that I've seen before include "Egypt's river" , "River at Luxor" , "African river" , "River of Egypt" , "World's longest river" .)