What does the cryptic crossword clue "Start work on mending stetson on head (3,4,4,2)" mean?

The wordplay uses an anagram. anagram of ON + STETSON + HEAD = SETONESHANDTO The answer is SETONESHANDTO.

Start work on mending stetson on head (3,4,4,2)

Daily Mail Cryptic #17169 | 15 Across | 2023-08-23 flower