Guy quits declining small rise (5)
I believe the answer is:
mound
'rise' is the definition.
(thesaurus)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for mound that I've seen before include "Knoll" , "Mass of piled-up earth or stones" , "Small hill, large pile" , "Earth bank" , "Raised mass of earth" .)