The most common and most likely answer to this crossword clue is the 5 letter word BUFFO
I've seen this crossword clue in The Daily Telegraph
B
U
F
F
O
More clues leading to the result BUFFO
Buddy explains!
The straight part
We know that "Comic opera singer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case comic opera singer = buffo.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 BUFFO mean?
BUFFO noun- A comic singer, particularly in comic opera