What does the cryptic crossword clue "Rain said to be irregular in Mediterranean island (8)" mean?

The definition is "island". The wordplay uses an anagram. anagram of RAIN + SAID = SARDINIA; definition: "island" The answer is SARDINIA.

Rain said to be irregular in Mediterranean island (8)

Daily Mail Cryptic #17113 | 16 Down | 2023-06-06 flower