The most common and most likely answer to this crossword clue is the 8 letter word UNSPOKEN
I've seen this crossword clue in Independent
U
N
S
P
O
K
E
N
More clues leading to the result UNSPOKEN
Buddy explains!

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 UNSPOKEN mean?
UNSPOKEN verb- To retract what one has spoken, to unsay.
- (sometimes postpositive) Not spoken; not said.
- (sometimes postpositive) Not formally articulated or stated; implicit or understood.