The French code-carriers backed republic (7)
I believe the answer is:
senegal
'republic' is the definition.
(I know that Senegal is a republic)
'the french code-carriers backed' is the wordplay.
'the french' becomes 'la' (one of the French words for 'the').
'code carriers' becomes 'genes' (I've seen this in another clue).
'backed' says the letters should be written backwards.
'la'+'genes'='lagenes'
'lagenes' in reverse letter order is 'SENEGAL'.
(Other definitions for senegal that I've seen before include "Land" , "Sea glen in the African state" , "West African country" , "Country surrounding the Gambia" , "Former French colony in Africa" .)