The most common and most likely answer to this crossword clue is the 8 letter word APOSTATE
I've seen this crossword clue in The Times
A
P
O
S
T
A
T
E
More clues leading to the result APOSTATE
- Rat initially attracted by rubbish put outside
- A job had for one leaving the fold
- Person losing faith in a job turned to food?
- Paul, for example, worried for the French renegade
- A job worried religious dissident
- Renegade contessa finally set for the future without duke
- Renegade RAF officer in a tizzy
- Turncoat’s article put away with mail
- Had to go after a Pole, one walking away from party?
- Turncoat given a job at head of enterprise
Buddy explains!

The straight part
We know that "one walking away from party?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one walking away from party? = apostate.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 APOSTATE mean?
APOSTATE noun- A person who has renounced a religion or faith.
- One who, after having received sacred orders, renounces his clerical profession.
- Guilty of apostasy.