The most common and most likely answer to this crossword clue is the 10 letter word TOP-FLIGHT
I've seen this crossword clue in The Times
T
O
P
-
F
L
I
G
H
T
More clues leading to the result TOP-FLIGHT
- Stairs to attic? Excellent
- Excellent way to reach the attic?
- Superior’s hasty departure on vessel from the east
- One spinning act of cowardice, perhaps, as high-class
- Drug rejected by learner in struggle to be excellent
- Half of police force needs a shake-up – it’s handled by strict superior
- First-class, Stairway to Heaven , possibly?
- Class-A drug taken up to escape
- Spinner’s trajectory is outstanding
- Leading thinker’s work on female brilliance is outstanding
Buddy explains!

The straight part
We know that "Class-A" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case class-a = top-flight.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 TOP-FLIGHT mean?
TOP-FLIGHT adjective- Of the highest rank, or peak of excellence
- In the highest division