Report can supply just the opposite (3,6)
I believe the answer is:
per contra
'just the opposite' is the definition.
(Italian phrase meaning 'on the contrary')
'report can supply' is the wordplay.
'supply' indicates an anagram (in a supple way).
'report'+'can'='reportcan'
'reportcan' is an anagram of 'PER CONTRA'.
(Other definitions for per contra that I've seen before include "Quite the reverse!" , "On opposite side (Lat.); co-partner (anag.)" .)