Operatic boatmen? (10)
I believe the answer is:
gondoliers
'operatic boatmen?' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for gondoliers that I've seen before include "Craftsmen" , "Venetian boatmen" , "Operatic boatmen?" , "G & S' alternative for "The King of Barataria"" , "Venice boatmen" .)