The most common and most likely answer to this crossword clue is the 6 letter word FIESTA
I've seen this crossword clue in The Times
F
I
E
S
T
A
More clues leading to the result FIESTA
- At first, everything in hand before a party
- Feast I prepared for carnival
- Church celebration that is held during fast, strangely
- Feast I prepared for Spanish celebration, say
- Celebration if taken over by French is awesome at the outset
- Girl is in France: a religious celebration
- Some selfies taken to show holiday
- Losing vote, fakes cheers for party
- In Florida’s borders, strange site for a carnival
- Holiday where female has afternoon nap topless
Buddy explains!

The straight part
We know that "Spanish celebration, say" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case spanish celebration, say = fiesta.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 FIESTA mean?
FIESTA noun- (In Spanish speaking countries) A religious festival.
- A festive occasion.