Venomous African snake (5)
I believe the answer is:
mamba
'venomous african snake' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for mamba that I've seen before include "Venomous African snake (often black)" , "Venomous Afr. snake" , "Venomous African tree snake" , "serpent" , "One's venomous" .)