Even a unit? (4)
I believe the answer is:
flat
I believe this is a double definition.
'even' is the first definition.
(similar in meaning)
'a unit?' is the second definition.
(I know that flat is a type of instrumentality)
(Other definitions for flat that I've seen before include "Apartment; even" , "Uninteresting - piece of scenery" , "character on the staff" , "Lacking interest" , "rooms exactly" .)