The most common and most likely answer to this crossword clue is the 9 letter word APOSTOLIC
I've seen this crossword clue in Independent
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More clues leading to the result APOSTOLIC
- Pauline for one has no way to stop a detailed government plan
- Like a succession of ministers?
- East German gripped by a force mostly related to preaching the gospel
- Cast polio out of New Testament characters
- Like followers of trashy soap to start loving its characters
- As papal succession, so topical after Reformation
- Coal pits with nothing in them yield description of twelve good men
Buddy explains!

The straight part
We know that "related to preaching the gospel" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case related to preaching the gospel = apostolic.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 APOSTOLIC mean?
APOSTOLIC adjective- Pertaining to apostles or their practice of teaching; pertaining to the apostles (of early Christianity) or their teachings.
- According to the doctrines of the apostles; delivered or taught by the apostles.
- Of or pertaining to the pope or the papacy; papal.
- Of or pertaining to the Catholic missions.