What does the cryptic crossword clue "Tone nurse altered privately (5,4)" mean?

The definition is "privately". The wordplay uses an anagram. anagram of TONE + NURSE = ENTRENOUS; definition: "privately" The answer is ENTRENOUS.

Tone nurse altered privately (5,4)

Daily Mail Cryptic #17146 | 16 Across | 2023-07-21 flower