Top of skirt has new waistband (4)
I believe the answer is:
sash
'waistband' is the definition.
(I know that waistband can be written as sash)
'top of skirt has new' is the wordplay.
'top of' indicates taking the first letters.
'new' is an anagram indicator.
The initial letter of 'skirt' is 's'.
'has' with letters rearranged gives 'ash'.
's'+'ash'='SASH'
(Other definitions for sash that I've seen before include "Cummerbund" , "Ribbon as a symbol of rank" , "Window frame - shoulder band" , "Girdle" , "Broad band, the one me father wore?" .)