The most common and most likely answer to this crossword clue is the 3 plus 6 letter word RUN ACROSS
I've seen this crossword clue in The Daily Telegraph
R
U
N
A
C
R
O
S
S
More clues leading to the result RUN ACROSS
- Article put out after race meet
- Meet rhyme for first clue?
- Unexpectedly encounter a mongrel under ladder
- Chance upon series with a cold chat show host
- Unexpectedly meet resistance – woman in angry mood
- The components of the answer here don’t meet!
- Rush over to meet
- Chance upon Arun out of sorts and cantankerous
Buddy explains!
The straight part
We know that "Unexpectedly meet" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case unexpectedly meet = run across.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.