Go off when people annoy, or ruffle (7)
I believe the answer is:
flounce
'ruffle' is the definition.
(I know that ruffle can be written as flounce)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for flounce that I've seen before include "Preen - trimming" , "Exaggerated walk" , "Stamp" , "An impatient annoyed movement or a deep frill" , "Strut" .)