Sharp's counterpart (4)
I believe the answer is:
flat
'sharp's counterpart' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for flat that I've seen before include "Apartment; even" , "Unnatural - uninteresting - apartment" , "lacking in taste" , "one or more in uniform" , "Even - somewhere to live" .)