Drink son has in convenient place (6)
I believe the answer is:
shandy
'drink' is the definition.
(I know that shandy is a type of drink)
'son has in convenient place' is the wordplay.
'son' becomes 's' (genealogical abbreviation for son).
'has' says to put letters next to each other.
'in convenient place' becomes 'handy'.
's'+'handy'='SHANDY'
(Other definitions for shandy that I've seen before include "Drink made of beer and lemonade" , "Beer-lemonade mix" , "Drink of ale and lemonade 96)" , "Light beer" , "Beer/lemonade mixture" .)