Crossword Genius

Tries this out, becoming most annoyed (9)

Ross

I believe the answer is:

shirtiest

'most annoyed' is the definition.
(I've seen this before)

'tries this out' is the wordplay.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'tries'+'this'='triesthis'
'triesthis' is an anagram of 'SHIRTIEST'.

'becoming' acts as a link.

(Another definition for shirtiest that I've seen is " Most annoyed".)

I've seen this clue in The Guardian.
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