What does the cryptic crossword clue "Walter's terrible spendthrift (7)" mean?

The definition is "spendthrift". The wordplay uses an anagram. anagram of WALTER'S = WASTREL; definition: "spendthrift" The answer is WASTREL.

Walter's terrible spendthrift (7)

Daily Mail Cryptic #17160 | 24 Across | 2023-08-10 flower