Undulating (4)
'undulating' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for wavy that I've seen before include "Sinuous" , "Rippled" , "Undulating" , "full of bends" , "Curly (hair)" .)
(Other definitions for hilly that I've seen before include "Not flat (country)" , "Descriptive of undulating upland" , "Mountainous" , "Unlike flat land" , "Like Chiltern or Cotswolds areas" .)
'undulating' is the definition.
('roll' can be a synonym of 'undulate')
This is all the clue.
(Other definitions for rolling that I've seen before include "Type of stock" , "Going round - a type of mill" , "extremely rich" , "-- Stock; -- pin" , "Steady and continuous" .)