What does the cryptic crossword clue "Go after version of Tosca in formal dress (9)" mean?

The wordplay uses an anagram. anagram of TAIL (synonym="go after") + TOSCA (synonym="TOSCA") = TAILCOATS The answer is TAILCOATS.

Go after version of Tosca in formal dress (9)

Guardian Cryptic #29623 | 2 Down | 2025-02-20 flower