Having beer on one's breath is quite OK! (4)
I believe the answer is:
hale
'one's breath is quite ok' is the definition.
I can't judge whether this definition defines the answer.
'having beer on' is the wordplay.
'having' becomes 'h' (this could be a standard abbreviation which I don't know about).
'beer' becomes 'ale' (type of beer).
'on' is a charade indicator (letters next to each other).
'h'+'ale'='HALE'
Can you help me to learn more?
(Other definitions for hale that I've seen before include "Healthy and robust" , "Sound of body" , "Well" , "Showing vigorous good health" , "Strong and healthy" .)