River of meandering line (4)
I believe the answer is:
nile
'river' is the definition.
(I know that Nile is a river)
'meandering line' is the wordplay.
'meandering' indicates anagramming the letters.
'line' with letters rearranged gives 'NILE'.
'of' acts as a link.
(Other definitions for nile that I've seen before include "River of eastern Africa" , "Take a line to the river" , "Egyptian river" , "'The longest river, blue and white (4)'" , "River that's Blue and White" .)