It protects an inventor's rights, that's obvious (6)
I believe the answer is:
patent
'obvious' is the definition.
(similar in meaning)
'it protects an inventor's rights' is the wordplay.
I cannot really understand how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is located in the answer.
'an' could be 'a' and 'a' is found in the answer.
The remaining letters 'pent' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for patent that I've seen before include "evident" , "Obvious - protection for inventors" , "Manifest" , "This leather has a glossy varnished surface" , "Registration of invention or trade-name" .)