Eighty percent included? That's kind (4)
I believe the answer is:
type
'kind' is the definition.
(type is a kind of kind)
'eighty percent included?' is the wordplay.
'included?' indicates a hidden word (I've seen 'include' mean this).
'TYPE' can be found hidden inside 'eighty percent'.
'that's' acts as a link.
(Other definitions for type that I've seen before include "Thing or person of a specified kind" , "Produce characters" , "The face" , "Use a keyboard; sort" , "Write using a keyboard" .)