The most common and most likely answer to this crossword clue is the 7 letter word PEGASUS
P
E
G
A
S
U
S
More clues leading to the result PEGASUS
- Matter about wise man looking up constellation
- Chatter behind gym, meeting American stars
- We’re stars, female, playing our parts?
- Stars secure as you and me?
- Herb in drink returned Medusa's offspring
- Stars stick with a controversial old law
- Winged horse in Winnipeg as usual
- Fabulous mount in South America doctor’s crossing east to west
- Strictly control a small American 4
- Marker put over a South American constellation
Buddy explains!

The straight part
We know that "Fabled horse" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case fabled horse = pegasus.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.