Before starting eating again, I had a notion (4)
I believe the answer is:
idea
'a notion' is the definition.
(both can mean a thought)
'before starting eating again i had' is the wordplay.
'before' is a charade indicator (letters next to each other).
'starting' says to take the initial letters.
'i had' becomes 'i'd' (I'd).
The initial letters of 'eating again' is 'ea'.
'ea' put after 'id' is 'IDEA'.
(Other definitions for idea that I've seen before include "Content of cognition" , "Proposal" , "Clue" , "Thought, conception" , "Suggestion" .)