Even — out of tune (4)
I believe the answer is:
flat
This clue is a double definition.
'even' is the first definition.
(similar in meaning)
'out of tune' is the second definition.
(I've seen this in another clue)
(Other definitions for flat that I've seen before include "place to live" , "Even -- pitched too low" , "Not hilly" , "Personal residence" , "Uninteresting - piece of scenery" .)