Watercourses in deserts (7)
I believe the answer is:
ditches
'watercourses in deserts' is the definition.
The definition and answer can be both man-made objects as well as being plural nouns.
Perhaps there's a link between them I don't understand?
'watercourses in deserts' is the wordplay.
'watercourses' becomes 'e' (I can't justify this - if you can you should believe this answer much more).
'in' means one lot of letters goes inside another.
'deserts' becomes 'ditchs' (ditching is a kind of deserting).
'e' going inside 'ditchs' is 'DITCHES'.
Can you help me to learn more?
(Other definitions for ditches that I've seen before include "Rejects" , "Gets rid of" , "Trenches" , "Long narrow channels" , "Abandons" .)