Thought of model, briefly (4)
I believe the answer is:
idea
'thought' is the definition.
(synonyms)
'model briefly' is the wordplay.
'model' becomes 'ideal' (ideal can mean model or perfect).
'briefly' means to remove the last letter.
'ideal' with its last letter taken away is 'IDEA'.
'of' is the link.
(Other definitions for idea that I've seen before include "Creative spark" , "Thought, conception" , "Notion, belief" , "intellectual product" , "Suggestion" .)