Landlady's character (6)
I believe the answer is:
letter
This clue is a double definition.
'landlady's' is the first definition.
(someone who lets)
'character' is the second definition.
(letter is a kind of character)
(Other definitions for letter that I've seen before include "Item sent - character" , "Written message" , "reference?" , "Alphabetic character" , "he leases" .)