What does the cryptic crossword clue "Niece Fern worked out deduction (9)" mean?

The definition is "deduction". The wordplay uses an anagram. anagram of NIECE + FERN = INFERENCE; definition: "deduction" The answer is INFERENCE.

Niece Fern worked out deduction (9)

Daily Mail Cryptic #17030 | 16 Down | 2023-02-09 flower