In all likelihood papers are South American, latest from Uruguay (1,4,3)
I believe the answer is:
i dare say
'in all likelihood' is the definition.
('I dare say' means you think something is likely)
'papers are south american latest from uruguay' is the wordplay.
'papers' becomes 'ID' (identification papers).
'south american' becomes 'SA'.
'latest from' says to take the final letters.
The final letter of 'uruguay' is 'y'.
'id'+'are'+'sa'+'y'='I DARE SAY'
(Other definitions for i dare say that I've seen before include "It wouldn't surprise me" , "Maybe" , "Probably" , "one might suppose" , "One assumes" .)