The most common and most likely answer to this crossword clue is the 8 letter word JEREPIGO
J
E
R
E
P
I
G
O
Buddy explains!

The straight part
We know that "Sweet wine" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sweet wine = jerepigo.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 JEREPIGO mean?
JEREPIGO noun- A sweet fortified wine.