What does the cryptic crossword clue "‘O Claudius’ is wrong? That’s harsh (9)" mean?

The wordplay uses an anagram. anagram of OCLAUDIUS ("'O Claudius'") [anagram: "wrong?"] = ACIDULOUS The answer is ACIDULOUS.

‘O Claudius’ is wrong? That’s harsh (9)

Guardian Cryptic #29642 | 15 Down | 2025-03-14 flower