What does the cryptic crossword clue "Sightseer is enthralled by trout, swimming (7)" mean?

The definition is "Sightseer". The wordplay uses an anagram. anagram of IS + TROUT, = TOURIST; definition: "Sightseer" The answer is TOURIST.

Sightseer is enthralled by trout, swimming (7)

Daily Mail Cryptic #16420 | 25 Across | 2020-10-08 flower