Concept (4)
'concept' is the definition.
(I know that idea is a type of concept)
This is all the clue.
(Other definitions for idea that I've seen before include "Notion, image" , "Thought, conception" , "Theory" , "Purpose" , "Notion, belief" .)
'concept' is the definition.
(I have seen 'A concept' mean 'thought' so perhaps 'concept' could also mean 'thought')
This is the entire clue.
(Other definitions for thought that I've seen before include "Performed brain operations" , "Study" , "Supposed" , "Cogitated" , "Thinking process" .)