What does the cryptic crossword clue "Nuts, alas, mistaken for fruit (8)" mean?

The definition is "fruit". The wordplay uses an anagram. anagram of NUTS, + ALAS, = SULTANAS; definition: "fruit" The answer is Sultanas.

Nuts, alas, mistaken for fruit (8)

Telegraph Prize Cryptic #3022 | 18 Across | 2019-09-22 flower