Wine from Brazilian port? Yes, in Berlin (5)
I believe the answer is:
'wine' is the definition.
(Rioja is an example)
'brazilian port? yes in berlin' is the wordplay.
'brazilian port?' becomes 'Rio' (Rio de Janeiro).
'yes in berlin' becomes 'ja' (I am not sure about this - if you are sure you should believe this answer much more).
'from' is the link.
Can you help me to learn more?
(Other definitions for rioja that I've seen before include "Spanish table wine" , "Spanish wine variety" , "Wine from northern Spain" , "Spanish drink" , "kind of red" .)