Note significant other is neither good nor bad (4)
I believe the answer is:
soso
'neither good nor bad' is the definition.
I don't know anything about this answer so I can't tell whether this works.
'note significant other' is the wordplay.
'note' becomes 'so' (musical note).
'significant other' becomes 'so' (this might be a standard abbreviation I've not previously seen).
'so'+'so'='SOSO'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for soso that I've seen before include "mediocre" , "Indifferent" .)