That woman has nothing but footwear (4)
I believe the answer is:
shoe
'footwear' is the definition.
(I know that shoe is a type of footwear)
'that woman has nothing' is the wordplay.
'that woman' becomes 'she' (she refers to a woman).
'has' indicates putting letters inside.
'nothing' becomes 'O' (looks like zero - 0).
'she' placed around 'o' is 'SHOE'.
'but' is the link.
(Other definitions for shoe that I've seen before include "Where a dealer stashes a pack" , "Playing card box" , "Slingback, for example" , "mule, perhaps?" , "Oxford, say" .)