Spirits provided by good landlords (6)
'spirits' is the definition.
(ghost is a kind of spirit)
'by good landlords' is the wordplay.
'by' says to put letters next to each other.
'good' becomes 'g' (abbreviation).
'landlords' becomes 'hosts' (I've seen this before).
'g' put next to 'hosts' is 'GHOSTS'.
'provided' acts as a link.
(Other definitions for ghosts that I've seen before include "Spooks, spectres", "Spirits or apparitions", "Spectres, wraiths", "Apparitions of a dead people", "Writes for another; Ibsen play".)