The most common and most likely answer to this crossword clue is the 8 letter word UNSEEDED
I've seen this crossword clue in The Sunday Telegraph
U
N
S
E
E
D
E
D
Buddy explains!
The straight part
We know that "Not expected to succeed at Wimbledon" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case not expected to succeed at wimbledon = unseeded.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 UNSEEDED mean?
UNSEEDED adjective- Not seeded (in any sense).
- Not being a seed, not being in a seed position.