A patient is better after it (8)

I believe the answer is:
recovery
'a patient' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'better after it' is the wordplay.
I cannot quite understand how this works, but
'better' could be 'recover' (recovering is a kind of bettering) and 'recover' is found in the answer.
A single letter 'y' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
'is' is the link.
Can you help me to learn more?
(Other definitions for recovery that I've seen before include "Green shoots could be a sign of this" , "Upturn" , "Convalescence" , "A return to good health" , "Rally" .)