Murder of two fools by one country (13)
I believe the answer is:
assassination
'murder' is the definition.
(assassination is a kind of murder)
'two fools by one country' is the wordplay.
'two fools' can mean two replacements for 'fool'.
'fool' becomes 'ass' (both can mean a stupid person).
'fool' becomes 'ass' (both can mean a stupid person).
'by' is a charade indicator (letters next to each other).
'one' becomes 'i' (Roman numeral).
'country' becomes 'nation' (synonyms).
'ass'+'ass'+'i'+'nation'='ASSASSINATION'
'of' acts as a link.
(Other definitions for assassination that I've seen before include "Murder of a public figure" , "Ordered killing" , "Murder of a prominent person" , "Merciful, lenient" , "Politically-inspired murder" .)