The most common and most likely answer to this crossword clue is the 10 letter word FORTHRIGHT
I've seen this crossword clue in The Sunday Telegraph
F
O
R
T
H
R
I
G
H
T
More clues leading to the result FORTHRIGHT
Buddy explains!

The straight part
We know that "outspoken" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case outspoken = forthright.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 FORTHRIGHT mean?
FORTHRIGHT noun- A straight path.
- Straightforward, not evasive, candid and direct.
- Frank, outspoken.
- Markedly simple.
- Fixed, settled, decided.
- Proceeding straight forth.
- Expressly, frankly, unhesitatingly.
- At once, forthwith.
- Swiftly.
- Straight forward, in a straight direction.