Good in spirit (3)
I believe the answer is:
gin
'spirit' is the definition.
(alcoholic spirit)
'good in' is the wordplay.
'good' becomes 'g' (abbreviation).
'g'+'in'='GIN'
(Other definitions for gin that I've seen before include "Liquor flavoured with juniper berries" , "Clear alcoholic drink" , "Juniper-flavoured spirit" , "Alcohol made with juniper berries" , "Alcoholic drink once known as mother's ruin" .)