The most common and most likely answer to this crossword clue is the 9 letter word MODERNISM
I've seen this crossword clue in The Daily Telegraph
M
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More clues leading to the result MODERNISM
Buddy explains!
The straight part
We know that "one form of theology" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one form of theology = modernism.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 MODERNISM mean?
MODERNISM noun- Modern or contemporary ideas, thought, practices, etc.
- Anything that is characteristic of modernity.
- Any of several styles of art, architecture, literature, philosophy, etc., that flourished in the 20th century.
- A religious movement in the early 20th century that tried to reconcile Roman Catholic dogma with modern science and philosophy.