The most common and most likely answer to this crossword clue is the 10 letter word FEDERALISM
I've seen this crossword clue in The Times
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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.
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What does FEDERALISM mean?
FEDERALISM noun- A system of national government in which power is divided between a central authority and a number of regions with delimited self-governing authority.
- Advocacy of such a system.
- Covenantalism.