Blow footwear! (4)
I believe the answer is:
sock
I believe this is a double definition.
'blow' is the first definition.
(I've seen this in another clue)
'footwear' is the second definition.
(sock is a kind of footwear)
(Other definitions for sock that I've seen before include "Item of clothing" , "Hit with a powerful blow" , "One worn" , "Foot garment" , "Hit; garment" .)