"Antony and Cleopatra" snake (3)
I believe the answer is:
asp
'antony and cleopatra snake' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for asp that I've seen before include "Poisonous type" , "Snake of the Nile" , "Joe Blake is Australian species" , "One secreting poison" , "Kind of snake - what a sap" .)