The most common and most likely answer to this crossword clue is the 10 letter word BARCAROLLE
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Buddy explains!

The straight part
We know that "song of Venice" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case song of venice = barcarolle.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 BARCAROLLE mean?
BARCAROLLE noun- A Venetian folk song traditionally sung by gondoliers, often in 6/8 or 12/8 time with alternating strong and weak beats imitating a rowing motion.
- A piece of music composed in imitation of such a song.