The Bard's "venomous fool" (3)
I believe the answer is:
asp
'the bard's venomous fool' 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 "Egyptian cobra" , "Kind of snake - what a sap" , "Slithery thing" , "the snake in Cleopatra''s bosom" , "Snake of the Nile" .)