The most common and most likely answer to this crossword clue is the 3 plus 10 letter word THE GONDOLIERS
I've seen this crossword clue in The Daily Telegraph
T
H
E
G
O
N
D
O
L
I
E
R
S
More clues leading to the result THE GONDOLIERS
- Ring in Rheingold set unconventionally as an operetta
- Quirky English rooted for home-grown opera
- Operetta delights one, or otherwise
- Stage work long theorised to be faulty
- First piece of opera singer told he must perform? Could be
- It could give singer toehold in career
- The delirious duo losing heart in role penned by G&S
- Hotels ignored comic opera
Buddy explains!
The straight part
We know that "Could be" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case could be = the gondoliers.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.