What does the cryptic crossword clue "24ac loos unfortunately out of use (8)" mean?

The wordplay uses an anagram. anagram of BEET (synonym="24ac") + LOOS (synonym="LOOS") = OBSOLETE The answer is OBSOLETE.

24ac loos unfortunately out of use (8)

Guardian Cryptic #29228 | 20 Across | 2023-11-15 flower