I say landlord's one who must make allowances (6)
I believe the answer is:
letter
This could be a double definition.
'i say landlord's' is the first definition.
'letter' can be an answer for 'landlord's' (landlords let property). I am unsure of the 'i say' bit.
'one who must make allowances' is the second definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
Can you help me to learn more?
(Other definitions for letter that I've seen before include "he leases" , "Character - mail - landlord" , "Written character - landlord" , "A written form of communication" , "Written message" .)