What does the cryptic crossword clue "Mixture, potato served to Mennonites, but no starter? (8)" mean?

The wordplay uses a charade (building blocks). MISH (synonym="Mennonites") + MASH (synonym="potatoes") = MISHMASH The answer is MISHMASH.

Mixture, potato served to Mennonites, but no starter? (8)

Guardian Cryptic #29235 | 16 Across | 2023-11-23 flower