Eccentricity of uneven quality (7)
I believe the answer is:
oddness
I believe this is a double definition.
'eccentricity' is the first definition.
(oddness is a kind of eccentricity)
'uneven quality' is the second definition.
(odd is the opposite of even)
'of' acts as a link.
(Other definitions for oddness that I've seen before include "It isn't even" , "Peculiarity characteristic" , "a peculiarity of character" , "Curious state" , "Peculiar quality" .)