Venomous snake in footwear (8)
I believe the answer is:
moccasin
I believe this is a double definition.
'venomous snake' is the first definition.
(I've seen this in another clue)
'footwear' is the second definition.
(I know this)
'in' acts as a link.
(Other definitions for moccasin that I've seen before include "American Indian shoe" , "Put one's foot in it" , "Footwear" , "Venomous American snake" , "Slipper; snake" .)