You could write one to the landlord (6)
I believe the answer is:
letter
'the landlord' is the definition.
(landlords let property)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for letter that I've seen before include "who may offer terms to residents?" , "Character; missive" , "Eg, A" , "Item sent - character" , "Character - landlord - epistle" .)