Landlord with brains printed notepaper (10)
I believe the answer is:
letterhead
'printed notepaper' is the definition.
(I've seen this before)
'landlord with brains' is the wordplay.
'landlord' becomes 'letter' (landlords let property).
'with brains' becomes 'head' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'letter'+'head'='LETTERHEAD'
Can you help me to learn more?
(Other definitions for letterhead that I've seen before include "Where name and address are shown" , "Address, name etc printed at top of notepaper" , "Printed address on stationery" , "Heading on stationery" , "Preprinted name, address etc at top of notepaper" .)