Old medicine finally changed for modern therapy (6)
I believe the answer is:
physio
'modern therapy' is the definition.
(physiotherapy)
I don't understand how the remainder of the clue works.
(Other definitions for physio that I've seen before include "One treats injuries with exercises etc., in short" , "One's paid to manhandle" , "Manipulative type" , "Masseuse maybe" , "manual worker" .)