Equine mammal (5)
(Other definitions for horse that I've seen before include "It may get people stoned" , "Nag, hack" , "Vaulting --; -- sense" , "eg Shire" , "Suffolk punch" .)
(Other definitions for zebra that I've seen before include "Kind of crossing?" , "Braze (anag.)" , "A striped pony-like African animal" , "Horse-like striped beast" , "Stripy member of horse family" .)