The most common and most likely answer to this crossword clue is the 7 letter word RAMADAN
R
A
M
A
D
A
N
More clues leading to the result RAMADAN
- Raced round like a loony, after a fast time
- A cuckoo coming in dashed fast
- Artist on island framing publicity notice fast
- Stuff a martial arts expert does for a month
- Graduate in drama school gaining name fast?
- Religious festival managed to include a cross
- Mother entering stage school gets lead in Norma fast
- Beastly male duck, flipping fast
- Fast hit by a karate expert
- Managed to hold the first man coming up fast
Buddy explains!

The straight part
We know that "fast" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fast = ramadan.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.