What does the cryptic crossword clue "Ridiculous brain an egghead possesses (5)" mean?

The definition is "Ridiculous". The wordplay uses a hidden word. Hidden in "ridiculous braIN AN Egghead possesses" The answer is Inane.

Ridiculous brain an egghead possesses (5)

Telegraph Prize Cryptic #3026 | 21 Across | 2019-10-20 flower