Cat trapping tails of mice in spite (5)
I believe the answer is:
venom
'spite' is the definition.
(synonyms)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for venom that I've seen before include "Poisonous liquid of snakes" , "Poisonous fluid" , "Snake's poison" , "Virulent feeling" , "Poison - spite" .)