Mammals known for their ability to spray unpleasant-smelling liquids in self-defence (6)
I believe the answer is:
skunks
(Other definitions for skunks that I've seen before include "American animals noted for foul smell" , "Despicable folk" , "Maladorous mammals" , "Evil-smelling animals from N America" , "American mammals that let out a smelly fluid in self-defence" .)