What does the cryptic crossword clue "It may be burnt — that's blooming insane! (6)" mean?

The definition is "It may be burnt". The wordplay uses an anagram. anagram of INSANE! = SIENNA; definition: "It may be burnt" The answer is SIENNA.

It may be burnt — that's blooming insane! (6)

Guardian Cryptic #29109 | 7 Down | 2023-06-29 flower