Cleopatra's killer
I believe the answer is:
'cleopatra's killer' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for asp that I've seen before include "Venomous snake" , "Cleopatra's supposed nemesis" , "Small poisonous snake" , "Small viper" , "Pa's Cleopatra's killer" .)