Disease-spreading insect (8)
I believe the answer is:
mosquito
'disease-spreading insect' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for mosquito that I've seen before include "Malaria transmitter" , "Sucker" , "possible disease carrier" , "Insect, the female of which sucks blood" , "Disease-bearing insect" .)