Spirits supplied by good landlords (6)
I believe the answer is:
ghosts
'spirits' is the definition.
(ghost is a kind of spirit)
'good landlords' is the wordplay.
'good' becomes 'g' (abbreviation).
'landlords' becomes 'hosts' (I've seen this before).
'g'+'hosts'='GHOSTS'
'supplied by' is the link.
(Other definitions for ghosts that I've seen before include "Spectres, wraiths" , "Spooks, spectres" , "Writes for another; Ibsen play" , "Apparitions of a dead people" , "Spirits or apparitions" .)