Foreign nation, old chap (7)
I believe the answer is:
antonio
'chap' is the definition.
'foreign nation old' is the wordplay.
'foreign' indicates anagramming the letters (foreign order of the letters).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'nation' is an anagram of 'antoni'.
'antoni'+'o'='ANTONIO'
(Other definitions for antonio that I've seen before include "sea captain in Twelfth Night" , "A notion about The Merchant of Venice" , "Italian chap" , "Pound of flesh promiser" , "-- Vivaldi, composer" .)