Free former partner, single before judge (9)
I believe the answer is:
exonerate
'free' is the definition.
(I've seen this before)
'former partner single before judge' is the wordplay.
'former partner' becomes 'ex' (an ex-partner).
'single' becomes 'one' (a single thing - only one).
'before' means one lot of letters go next to another.
'judge' becomes 'rate' (rating is a kind of judging).
'ex'+'one'+'rate'='EXONERATE'
(Other definitions for exonerate that I've seen before include "Acquit" , "Justify" , "Declare to be blameless (9)" , "free of charge" , "let off the hook" .)