Well past one's prime yet still making progress (7,2)
I believe the answer is:
getting on
'making progress' is the definition.
('get on' can be a synonym of 'make progress')
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for getting on that I've seen before include "Like group of friends" , "as a boarder > in later years?" , "no longer young" , "Elderly; succeeding" , "Enjoying friendly relations" .)