Ripening, maturing (6)
I believe the answer is:
ageing
This clue is a double definition.
'ripening' is the first definition.
(synonyms)
'maturing' is the second definition.
('age' can be a synonym of 'mature')
(Other definitions for ageing that I've seen before include "Getting old" , "Elderly" , "Getting older" , "Growing old" , "process of development" .)