Idiot turned up? Refuse to receive one contribution to thinking, perhaps (8)

'contribution to thinking perhaps' is the definition.
I can't judge whether this definition defines the answer.

'idiot turned up? refuse to receive one' is the wordplay.
'idiot' becomes 'dim' (both can mean stupid).
'turned up?' shows that the letters should be reversed in order.
'refuse' becomes 'bran' (I've seen this before).
'to receive' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'dim' in reverse letter order is 'mid'.
'bran' going around 'i' is 'brain'.
'mid'+'brain'='MIDBRAIN'

Can you help me to learn more?