What does the cryptic crossword clue "Tries this out, becoming most annoyed (9)" mean?

The wordplay uses an anagram. anagram of TRIES (synonym="TRIES") + THIS (synonym="THIS") = SHIRTIEST The answer is SHIRTIEST.

Tries this out, becoming most annoyed (9)

Guardian Cryptic #29384 | 14 Down | 2024-05-16 flower