Narcotics failing to impress a Central American (5,5)
I believe the answer is:
costa rican
'central american' is the definition.
(Costa Rican is an example)
'narcotics failing to impress a' is the wordplay.
'failing' indicates an anagram.
'to impress' means one lot of letters goes inside another (impress can mean enlist or recruit).
'narcotics' with letters rearranged gives 'costrican'.
'costrican' enclosing 'a' is 'COSTA-RICAN'.
(Other definitions for costa rican that I've seen before include "Foreign" , "Countryman" , "from Central America" , "Central American" , "South American" .)