Wine and port on top of unfinished beer (5)
I believe the answer is:
rioja
'wine' is the definition.
(Rioja is an example)
'port on top of unfinished beer' is the wordplay.
'port on top' becomes 'rio' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'of unfinished' means to remove the last letter (I've seen 'unfinished' mean this).
'beer' becomes 'jar' (I've seen this before).
'jar' with its last letter taken off is 'ja'.
'rio'+'ja'='RIOJA'
'and' is the link.
Can you help me to learn more?
(Other definitions for rioja that I've seen before include "Spanish red wine" , "wine region" , "Dry red wine from Spain" , "Spanish table wine" , "Spanish drink" .)