Meandering line by waterway (4)
I believe the answer is:
nile
'waterway' is the definition.
The definition and answer can be both natural objects as well as being singular nouns.
Maybe there's a link between them I don't understand?
'meandering line' is the wordplay.
'meandering' indicates anagramming the letters.
'line' is an anagram of 'NILE'.
'by' acts as a link.
Can you help me to learn more?
(Other definitions for nile that I've seen before include "White or Blue river of Africa" , "River associated with Cleopatra" , "white flower?" , "'The longest river, blue and white (4)'" , "Take a line to the river" .)