What does the cryptic crossword clue "Top deal in order for diminutive swimmer (7)" mean?

The definition is "swimmer". The wordplay uses an anagram. anagram of TOP + DEAL = TADPOLE; definition: "swimmer" The answer is TADPOLE.

Top deal in order for diminutive swimmer (7)

Daily Mail Cryptic #17385 | 23 Across | 2024-06-21 flower