What does the cryptic crossword clue "Poison can be extracted from a protein (8)" mean?

The definition is "Poison". The wordplay uses an anagram. anagram of A + PROTEIN = ATROPINE; definition: "Poison" The answer is ATROPINE.

Poison can be extracted from a protein (8)

Daily Mail Cryptic #16874 | 31 Across | 2022-07-06 flower