Winding line of waterway (4)
I believe the answer is:
nile
'waterway' is the definition.
The answer and definition can be both natural objects as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'winding line' is the wordplay.
'winding' is an anagram indicator.
'line' is an anagram of 'NILE'.
'of' is the link.
Can you help me to learn more?
(Other definitions for nile that I've seen before include "Long river" , "long-distance runner in Africa" , "Line (anag)" , "River of Egypt" , "Green" .)