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.
('patent' can be similar in meaning to 'obvious')
'that's' is the 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" .)