Viper types (4)
I believe the answer is:
asps
'viper types' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for asps that I've seen before include "native Africans?" , "because of their venom?" , "Pass (anag)" , "Poisonous snakes" , "Small venomous snakes" .)