Flower — Bertie Wooster's aunt (6)

I believe the answer is:

dahlia

(Other definitions for dahlia that I've seen before include "Showy herbaceous perennial" , "Wooster's aunt" , "Flower, often ball-shaped" , "Tuberous garden plant" , "Lia had this strange flower" .)

I've seen this clue in The Guardian.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.