The Guardian's going to fill top post, offering good facilities (4-9)
I believe the answer is:
well-appointed
'offering good facilities' is the definition.
'the guardian's going to fill top post' is the wordplay.
I cannot quite understand how this works, but
'going to' could be 'll' (as in he'll, we'll etc) and 'll' is present in the answer.
This explanation may well be incorrect...
(Other definitions for well-appointed that I've seen before include "Fully equipped" , "(Of room/building) finely fitted-out" , "Properly supplied" .)