What does the cryptic crossword clue "Transfer of jailed mob due in 2012 say (14)" mean?

The wordplay uses an anagram. anagram of JAILED + MOB + DUE + IN = DIAMONDJUBILEE The answer is DIAMONDJUBILEE.

Transfer of jailed mob due in 2012 say (14)

Independent Cryptic #11721 | 24 Across | 2024-05-04 flower