Cocktail: good drink quaffed by sweet Fanny Adams? (4,6)
I believe the answer is:
pina colada
'cocktail' is the definition.
(I've seen this before)
'good drink quaffed by sweet fanny adams?' is the wordplay.
'good' becomes 'pi' (old-fashioned term for pious).
'drink' becomes 'cola' (cola is a type of drink).
'quaffed by' means one lot of letters goes inside another (inserted letters are drunk or quaffed by others).
'sweet fanny adams?' becomes 'nada' (both can mean 'nothing').
'cola' going within 'nada' is 'nacolada'.
'pi'+'nacolada'='PINA COLADA'
(Other definitions for pina colada that I've seen before include "Cocktail of rum, pineapple juice and coconut" , "alcoholic one" , "Perhaps contents of cocktail glass" , "rum-based potation" , "Drink made of pineapple juice, coconut cream and rum" .)