Flounce downstairs after coat (8)
I believe the answer is:
furbelow
'flounce' is the definition.
('furbelow' can be a synonym of 'flounce')
'downstairs after coat' is the wordplay.
'downstairs' becomes 'below' ('below' can be a synonym of 'downstairs').
'after' is a charade indicator (letters next to each other).
'coat' becomes 'fur' (fur is a kind of coat).
'below' put after 'fur' is 'FURBELOW'.
(Other definitions for furbelow that I've seen before include "decoration for skirt, one gathered" , "superfluous ornament!" , "Flounce, frill" , "Ornamental trim" , "Old-fashioned border of a skirt or petticoat" .)