The most common and most likely answer to this crossword clue is the 6 letter word RIOJAS
I've seen this crossword clue in The Daily Telegraph
R
I
O
J
A
S
More clues leading to the result RIOJAS
Buddy explains!

The straight part
We know that "Spanish wines" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case spanish wines = riojas.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does RIOJAS mean?
RIOJAS noun- The wine (mostly red) of that region