What does the cryptic crossword clue "Soil retains dry composition (8)" mean?

The wordplay uses a container (one word inside another). SERE (synonym="‘dry’") in MIRE (synonym="‘soil’") = MISERERE The answer is MISERERE.

Soil retains dry composition (8)

Guardian Cryptic #29431 | 4 Down | 2024-07-10 flower