Hooded snake (5)
I believe the answer is:
cobra
'hooded snake' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cobra that I've seen before include "Type of snake" , "Reptile (found in Cabinet Office Briefing Room A?)" , "One with hood" , "Venomous hooded snake" , "Hooded snake - AC model of old sports car" .)