Region without hills, lacking beauty (5)
I believe the answer is:
plain
'hills lacking beauty' 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?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for plain that I've seen before include "Clear, candid" , "lament" , "Not decorated" , "Unadorned, not elaborate" , "Unflavoured" .)