Clear former partner, one on charge (9)
I believe the answer is:
exonerate
'clear' is the definition.
(I've seen this before)
'former partner one on charge' is the wordplay.
'former partner' becomes 'ex'.
'on' says to put letters next to each other.
'charge' becomes 'rate' (rate is a kind of charge**).
'ex'+'one'+'rate'='EXONERATE'
(Other definitions for exonerate that I've seen before include "free of charge" , "Clear of blame" , "Excuse" , "Release" , "Pronounce not guilty of a crime" .)