A thought I had for each (4)
I believe the answer is:
idea
'a thought' is the definition.
(I know that thought can be written as idea)
'i had for each' is the wordplay.
'i had' becomes 'I'd' (contraction).
'for' says to put letters next to each other.
'each' becomes 'ea' (abbreviation).
'id'+'ea'='IDEA'
(Other definitions for idea that I've seen before include "Thought or notion (4)" , "Sudden inspiration?" , "Inkling" , "It comes to mind" , "Creative spark" .)