What does the cryptic crossword clue "Confident set varies after reorganisation (9)" mean?

The definition is "Confident". The wordplay uses an anagram. anagram of SET + VARIES = ASSERTIVE; definition: "Confident" The answer is ASSERTIVE.

Confident set varies after reorganisation (9)

Daily Mail Cryptic #17550 | 14 Across | 2025-02-07 flower