Dull accommodation (4)
I believe the answer is:
flat
I believe this is a double definition.
'dull' is the first definition.
(similar in meaning)
'accommodation' is the second definition.
(type of residence)
(Other definitions for flat that I've seen before include "Uninteresting - piece of scenery" , "Not sloping; apartment" , "Unnatural - uninteresting - apartment" , "without qualification" , "place to live" .)