Energetic activity (6)
I believe the answer is:
bustle
'energetic activity' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for bustle that I've seen before include "Energetic activity" , "Hurried activity - old padded support for woman's dress" , "Hurried and noisy activity" , "Excited activity of subtle kind" , "Busy activity; old skirt padding" .)