The most common and most likely answer to this crossword clue is the 11 letter word VALEDICTORY
I've seen this crossword clue in The Times
V
A
L
E
D
I
C
T
O
R
Y
More clues leading to the result VALEDICTORY
Buddy explains!

The straight part
We know that "Final" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case final = valedictory.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 VALEDICTORY mean?
VALEDICTORY noun- A speech given by a valedictorian at a graduation or commencement ceremony.
- A farewell or parting address.
- Of, or pertaining to, a valedictorian.
- Bidding farewell; suitable or designed for an occasion of leave-taking.