The most common and most likely answer to this crossword clue is the 3 plus 6 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
- First class work following conclusion of trial in tense case
- Champion returned prize following match?
- Best turkey drunk, according to Spooner?
- Final steps up to roof? Excellent
- Elite Spooner’s drunk after fiasco
- Steps to attic of the highest class
- Excellent marijuana on reflection, starting to feel cheerful
- Champion in great escape
Buddy explains!

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