What does the cryptic crossword clue "Delicate sieve isn't working (9)" mean?

The definition is "Delicate". The wordplay uses an anagram. anagram of SIEVE + ISN'T = SENSITIVE; definition: "Delicate" The answer is SENSITIVE.

Delicate sieve isn't working (9)

Daily Mail Cryptic #16941 | 14 Down | 2022-10-07 flower