A patient improvement, perhaps (8)
I believe the answer is:
recovery
'a patient improvement' is the definition.
'recovery' can be an answer for 'improvement' (recovery is a kind of improvement). I am not sure about the 'a patient' bit.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for recovery that I've seen before include "A return to good health" , "Retrieval or recuperation" , "Retrieval - restoration of health" , "Improvement" , "Rally" .)