Giraffe-like animals with shorter necks (6)
I believe the answer is:
okapis
'giraffe-like animals with shorter necks' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for okapis that I've seen before include "They're like giraffes only smaller" , "African mammals" , "Giraffe-like animals with shorter necks" , "Giraffe-like creatures" , "Ok, Pa is wrong about the giraffe-type animals" .)