Two foreign articles get signature in secret (9)
I believe the answer is:
underhand
'in secret' is the definition.
(I've seen this before)
'two foreign articles get signature' is the wordplay.
'two foreign articles' becomes 'under' (I am not sure about this - if you are sure you should believe this answer much more).
'get' says to put letters next to each other.
'signature' becomes 'hand' (hand can mean someone's handwriting).
'under'+'hand'='UNDERHAND'
(Other definitions for underhand that I've seen before include "delivery may be so made" , "Crafty" , "done deviously through cover" , "Surreptitious" , "Sneaky" .)