I recant after conversion, for sure (7)
I believe the answer is:
certain
'sure' is the definition.
('certain' can be similar in meaning to 'sure')
'i recant after conversion' is the wordplay.
'after conversion' is an anagram indicator (I've seen this in other clues).
'i'+'recant'='irecant'
'irecant' anagrammed gives 'CERTAIN'.
'for' acts as a link.
(Other definitions for certain that I've seen before include "Proved beyond doubt" , "Indisputable" , "Convinced" , "Unquestionable" , "Assured" .)