What does the cryptic crossword clue "The Dandy or its rival's not half posh (4)" mean?

The definition is "Dandy". The wordplay uses a charade (building blocks). BEA (synonym="no's") + U (synonym=""posh"") = BEAU The answer is BEAU.

The Dandy or its rival's not half posh (4)

Guardian Cryptic #29298 | 23 Down | 2024-02-06 flower