There's no end of unstable footwear (7)
I believe the answer is:
slipper
'footwear' is the definition.
(slipper is a kind of footwear)
'there's no end of unstable' is the wordplay.
'there's no end of' means to remove the last letter.
'unstable' becomes 'slippery'.
'slippery' with its final letter taken off is 'SLIPPER'.
(Other definitions for slipper that I've seen before include "Indoor shoe" , "Ripples (anag.)" , "pump" , "Comfortable shoe" , "Casual indoors shoe" .)