Guaranteed (7)
(Other definitions for certain that I've seen before include "Convinced" , "Nice art (anag)" , "Decided" , "Sure; specific" , "Assured" .)
'guaranteed' is the definition.
('assure' can be a synonym of 'guarantee')
This is the entire clue.
(Other definitions for assured that I've seen before include "Confident - certain" , "Promised, guaranteed" , "without doubt" , "Secured" , "Gave confidence to" .)
'guaranteed' is the definition.
('ensure' can be a synonym of 'guarantee')
This is the entire clue.
(Other definitions for ensured that I've seen before include "Made certain for end user" , "Saw to it" , "Made certain, clinched" , "Determined" , "guaranteed" .)