Large wasp (6)
I believe the answer is:
'large wasp' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for hornet that I've seen before include "Throne for a kind of wasp" , "Throne (anag.)" , "Large wasp with vicious sting" , "A large wasp with serious sting" , "Large stinging wasp" .)