Neither good nor bad (2-2)
I believe the answer is:
so-so
'neither good nor bad' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for so-so that I've seen before include "Of average quality" , "Indifferently good" , "just about adequate" , "Tolerable, indifferent" , "Fair to middling" .)