Show contempt and endless malevolence (4)
I believe the answer is:
spit
'show contempt' is the definition.
(I've seen this before)
'endless malevolence' is the wordplay.
'endless' means to remove the last letter.
'malevolence' becomes 'spite' (spite is a kind of malevolence).
'spite' with its final letter taken off is 'SPIT'.
'and' is the link.
(Other definitions for spit that I've seen before include "23-ing implement" , "Coastal feature, tongue of sand" , "double, perhaps" , "A spade's depth, in earth" , "Metal rod for roasting meat" .)