Thought it would be back in time (6)
I believe the answer is:
notion
'thought' is the definition.
(notion is a kind of thought)
'would be back in time' is the wordplay.
'would be back' becomes 'ti' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' means one lot of letters goes inside another.
'time' becomes 'noon' (noon is a kind of time).
'ti' put into 'noon' is 'NOTION'.
'it' acts as a link.
This may not be correct. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for notion that I've seen before include "Idea, concept" , "Vague impression" , "An idea or casual thought" , "Idea or whim" , "Caprice" .)