Sure it’s a yes? (8)
I believe the answer is:
positive
I believe this is a double definition.
'sure' is the first definition.
('positive' can be similar in meaning to 'sure')
'a yes?' is the second definition.
(thesaurus)
'it's' is the link.
(Other definitions for positive that I've seen before include "sort of image" , "Definite, confident" , "Very sure, certain" , "Sure, convinced" , "Definite, sure" .)