It turns up in time to give you an idea (6)
I believe the answer is:
notion
'an idea' is the definition.
(I know that notion is a type of idea)
'it turns up in time' is the wordplay.
'turns up' says the letters should be written in reverse.
'in' means one lot of letters goes inside another.
'time' becomes 'noon' (noon is a kind of time).
'it' backwards is 'ti'.
'ti' inserted within 'noon' is 'NOTION'.
'to give you' acts as a link.
(Other definitions for notion that I've seen before include "Vague or whimsical idea" , "Vague impression" , "Idea or fancy" , "Concept, belief" , "desire" .)