Nothing east 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 there's a link between them I don't understand?
'nothing east' is the wordplay.
'nothing' becomes 'nil' (eg nil is zero in football).
'east' becomes 'e' (abbreviation).
'nil'+'e'='NILE'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for nile that I've seen before include "River of Egypt" , "River of eastern Africa" , "Green" , "River associated with Cleopatra" , "Cleopatra's river" .)