The most common and most likely answer to this crossword clue is the 6 letter word CARMEN
I've seen this crossword clue in The Daily Telegraph
C
A
R
M
E
N
More clues leading to the result CARMEN
- Transport workers' opera?
- Operatic MOT mechanics
- Opera for 6 across 18?
- Girl auto enthusiasts?
- Opera dealing with loveless romance?
- Heroine employed at Bentley?
- Drivers having a jolly in French city
- Female gypsy with chaps hiding under vehicle
- Side entrance in church has name of opera
- Those originally inside Rolls-Royce arriving at opera?
Buddy explains!

The straight part
We know that "Opera" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case opera = carmen.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 CARMEN mean?
CARMEN noun- A person who transported goods, usually with a horse and cart.