The one involved in Cleopatra's passing? (3)
I believe the answer is:
asp
'the one' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'involved in cleopatra's passing?' is the wordplay.
'involved in' says the answer is hidden in the clue.
'ASP' can be found hidden inside 'cleopatras passing'.
Can you help me to learn more?
(Other definitions for asp that I've seen before include "Snake found in spa" , "Slithery thing" , "Snake, killed Cleopatra" , "It proved deadly for Cleopatra" , "Serpent" .)