The most common and most likely answer to this crossword clue is the 11 letter word PROLEGOMENA
P
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A
Buddy explains!
The straight part
We know that "Preliminary discussions" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case preliminary discussions = prolegomena.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 PROLEGOMENA mean?
PROLEGOMENA noun- (usually in the plural) A prefatory discussion; a formal essay or critical discussion serving to introduce and interpret an extended work.