In France, you double the skirt (4)
I believe the answer is:
tutu
'the skirt' is the definition.
(tutu is a kind of skirt)
'in france you double' is the wordplay.
'in france you' becomes 'tu' ('you' in French).
'double' indicates the doubling of some letters.
'tu' doubled is 'TUTU'.
(Other definitions for tutu that I've seen before include "A ballerina's short skirt" , "Ballet dancer's costume" , "Ballerina's stiff skirt" , "Giselle's skirt" , "Female ballet costume" .)