The most common and most likely answer to this crossword clue is the 13 letter word PRIMOGENITURE
I've seen this crossword clue in Independent
P
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M
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Buddy explains!
The straight part
We know that "Arrangement for continuation of leaders" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case arrangement for continuation of leaders = primogeniture.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 PRIMOGENITURE mean?
PRIMOGENITURE noun- The state of being the firstborn of the children of the same parents.
- The principle that the eldest child has an exclusive right of inheritance.
- An instance of such a right of inheritance, established by custom or law.