Maturing makes a drink good (5)
I believe the answer is:
aging
'maturing' is the definition.
(I've seen this in another clue)
'a drink good' is the wordplay.
I cannot really see how this works, but
'a' is within the answer.
'drink' could be 'gin' (gin is an alcoholic drink) and 'gin' is found in the answer.
'good' could be 'g' (abbreviation) and 'g' is found in the answer.
No letters remain.
This explanation may well be incorrect...
'makes' acts as a link.
Can you help me to learn more?
(Other definitions for aging that I've seen before include "Getting old" , "Becoming more grown-up" , "in decline" , "Getting older" , "Growing old in the US" .)