What does the cryptic crossword clue "Reformer grabbed by Schoenberg or Bach even (9)" mean?

The wordplay uses a hidden word. A hidden answer (‘grabbed by’) in ‘Schoenber G OR BACH EV en’. The answer is GORBACHEV.

Reformer grabbed by Schoenberg or Bach even (9)

Guardian Cryptic #29417 | 15 Across | 2024-06-24 flower