The most common and most likely answer to this crossword clue is the 8 letter word CARNIVAL
I've seen this crossword clue in The Times
C
A
R
N
I
V
A
L
More clues leading to the result CARNIVAL
- Erotic setting for one opposed to jamboree
- Fiesta motor, new, a line accommodating four
- Dvorak overture showing family vehicle in perpetual snow
- Northern vicar organised a large street party
- Regularly bring in sparkling wine to entertain large street party
- Four sexy dresses for Brazilian party, say?
- Foursome involved in erotic festival
- One very impressed by sensual and riotous feasting
- One very absorbed by erotic entertainment
- Can rival working for travelling fair
Buddy explains!

The straight part
We know that "Fiesta" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fiesta = carnival.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 CARNIVAL mean?
CARNIVAL noun- Any of a number of festivals held just before the beginning of Lent.
- A festive occasion marked by parades and sometimes special foods and other entertainment.
- A traveling amusement park, called a funfair in British English.