What does the cryptic crossword clue "Firm with smoking gun? Fit with a silencer? (10)" mean?

The wordplay uses a charade (building blocks). SOUND (synonym="firm") + PROOF (synonym="smoking gun") = SOUNDPROOF The answer is SOUNDPROOF.

Firm with smoking gun? Fit with a silencer? (10)

Guardian Cryptic #29322 | 13 Across | 2024-03-05 flower