Type of leather, that's obvious (6)
I believe the answer is:
patent
This clue is a double definition.
'type of leather' is the first definition.
'obvious' is the second definition.
(similar in meaning)
'that's' acts as a link.
(Other definitions for patent that I've seen before include "It's registered to protect an invention" , "It protects an invention" , "Sole right to exploit an invention" , "The invention protection is obvious" , "For all to see" .)