Framework that's kind of key (8)
I believe the answer is:
skeleton
I believe this clue is a double definition.
'framework' is the first definition.
(I've seen this before)
'kind of key' is the second definition.
(I've seen this before)
'that's' is the link.
(Other definitions for skeleton that I've seen before include "person in no danger of looking fat!" , "Body's framework" , "set of bones?" , "one doesn't want found in cupboard" , "Frame - secret scandal" .)