Dancer's skirt (4)
I believe the answer is:
tutu
'dancer's skirt' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for tutu that I've seen before include "Ballet dancer's short skirt" , "Ballerina's costume" , "Ballerina's stiff skirt" , "Short dress" , "Short skirt for ballet dancer" .)