Convinced it's inevitable (7)
I believe the answer is:
certain
I believe this clue is a double definition.
'convinced' is the first definition.
(similar in meaning)
'inevitable' is the second definition.
(similar in meaning)
'it's' acts as a link.
(Other definitions for certain that I've seen before include "Proved beyond doubt" , "Particular" , "Quite sure, positive" , "Unquestionable" , "Assured" .)