The most common and most likely answer to this crossword clue is the 9 letter word CATECHISM
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More clues leading to the result CATECHISM
- Teach music abroad, ditching posh teaching method
- Problem is Mass involving eastern religious instruction
- Religious instruction for Catholic? Problem is Mass without English
- Religious instruction that could be schematic
- Religious teaching restored ethics in University briefly
- Series of questions schematic in arrangement
- Questions of a religious nature caught a chemist out
- Interrogation from Persian possibly chimes awkwardly
- Flawed schematic gives rise to lots of questions
- Schematic representation of set of religious principles
Buddy explains!

The straight part
We know that "Interrogation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case interrogation = catechism.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 CATECHISM mean?
CATECHISM noun- A book, in question and answer form, summarizing the basic principles of Christianity.
- A basic manual in some subject.
- A set of questions designed to determine knowledge.