What does the cryptic crossword clue "Onlooker showing awful brass, yep (6,2)" mean?

The wordplay uses an anagram. anagram of BRASS, + YEP = PASSERBY The answer is PASSERBY.

Onlooker showing awful brass, yep (6,2)

Daily Mail Cryptic #17059 | 1 Across | 2023-03-22 flower