Positive or negative news about old love (3-4)
I believe the answer is:
non-zero
'positive or negative' is the definition.
(I've seen this before)
'news about old love' is the wordplay.
'news' becomes 'nn' (the abbreviation for 'new' written twice).
'about' is an insertion indicator.
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'love' becomes 'zero' (love is zero in tennis).
'nn' placed around 'o' is 'non'.
'non'+'zero'='NON-ZERO'
(Other definitions for non-zero that I've seen before include "Either positive or negative" , "Having a positive or negative value, ie anything not equating to nought (mathematics)" .)