Drink for son, German, at start of the year (6)
I believe the answer is:
sherry
'drink' is the definition.
(sherry is a kind of drink)
'son german at start of the year' is the wordplay.
'son' becomes 's'.
'german' becomes 'herr'.
'at start of' suggests taking the first letters (I've seen 'at start' mean this).
The initial letter of 'year' is 'y'.
's'+'herr'+'y'='SHERRY'
'for' acts as a link.
(Other definitions for sherry that I've seen before include "Alcohol for the trifle" , "Amontillado, e.g." , "Christmas drink?" , "Preprandial drink" , "Wine from the Jerez region of Spain" .)