Guard housed by private landlord (9)
I believe the answer is:
innkeeper
'landlord' is the definition.
(I've seen this before)
'guard housed by private' is the wordplay.
'guard' becomes 'keep guard' (keeping guard is a kind of guarding).
'housed by' is an insertion indicator.
'private' becomes 'inner' (as in one's private or inner thoughts).
'keep' going inside 'inner' is 'INNKEEPER'.
(Other definitions for innkeeper that I've seen before include "Pub licensee" , "Manager who made extra provision for visitors" , "local manager" , "Job" , "Mine host" .)