What does the cryptic crossword clue "Boob reflected in mirror regrettably (5)" mean?

The definition is "Boob". The wordplay uses a hidden word. Hidden reversed in "boob reflected in mirROR REgrettably" The answer is ERROR.

Boob reflected in mirror regrettably (5)

Independent Cryptic #11836 | 22 Down | 2024-09-16 flower