Convinced (4)
'convinced' is the definition.
(similar in meaning)
This is the entire clue.
(Other definitions for certain that I've seen before include "Assured" , "Proved beyond doubt" , "Absolutely sure" , "Sure, definite" , "Known beyond doubt" .)
'convinced' is the definition.
('assure' can be a synonym of 'convince')
This is all the clue.
(Other definitions for assured that I've seen before include "Self-confident" , "Promised, guaranteed" , "Exhibiting confidence" , "Confident and self-possessed" , "Gave confidence to" .)
'convinced' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for sure that I've seen before include "Positive" , "Definite" , "The old sewer" , "stable" , "Agreed" .)