Big city German's agreeable expression offering wine (5)
I believe the answer is:
rioja
'wine' is the definition.
(I know that Rioja is a type of red wine)
'big city german's agreeable expression' is the wordplay.
'big city' becomes 'Rio' (Rio de Janeiro).
'german's agreeable expression' becomes 'Ja' (German for 'yes').
'rio'+'ja'='RIOJA'
'offering' acts as a link.
(Other definitions for rioja that I've seen before include "Wine from northern Spain" , "Spanish wine type" , "Spanish red wine" , "wine region" , "Spanish drink" .)