What does the cryptic crossword clue "Throw out joint set in need of replacement (8)" mean?

The definition is "Throw". The wordplay uses an anagram. anagram of JOINT + SET = JETTISON; definition: "Throw" The answer is JETTISON.

Throw out joint set in need of replacement (8)

Daily Mail Cryptic #17392 | 11 Across | 2024-07-02 flower