What does the cryptic crossword clue "Sweet rum and Asti I mixed up (8)" mean?

The definition is "Sweet". The wordplay uses an anagram. anagram of RUM + ASTI + I = TIRAMISU; definition: "Sweet" The answer is Tiramisu.

Sweet rum and Asti I mixed up (8)

Telegraph Prize Cryptic #3128 | 16 Across | 2021-10-03 flower