Possible Clues:

• Venetian landmark
• Venice landmark
• 'Largely, by the sound of it, a sad way over in Venice (6,2,5)'
• 'Sounds big, sounds sad, is over the canal (6,2,5)'
• Samuel Beckett, for one, has nothing to do with loud moans witnessed way over on a tour of Venice
• Violin part aged with scale in auditorium, Italian landmark
• Over which Venetian prisoners were led to trial
• Prison passage sounds too big to cross
• Venice tourist attraction
• Huge feat of engineering said to be feature of Venice