Attractive of course, and quite certain (6,4)

I believe the answer is:

pretty sure

'quite certain' is the definition.
(pretty sure or certain about something)

'attractive of course' is the wordplay.
'attractive' becomes 'pretty' (pretty can mean good-looking or attractive).
'of course' becomes 'sure' (I've seen this before).
'pretty'+'sure'='PRETTY SURE'

'and' acts as a link.

I've seen this clue in The Telegraph.

Want a hint initially instead of a full solution? Install my app