Country's spies turned, lust comes first (2,5)
I believe the answer is:
st lucia
'country's' is the definition.
(St. Lucia is an example)
'spies turned lust comes first' is the wordplay.
'spies' becomes 'cia' (Central Intelligence Agency).
'turned' indicates anagramming the letters.
'comes first' says to put letters next to each other.
'lust' is an anagram of 'stlu'.
'cia' put after 'stlu' is 'ST LUCIA'.
(Other definitions for st lucia that I've seen before include "Commonwealth country in the Windward Islands" , "Windward Isles country to the south of Martinique" , "Caribbean country" , "'Volcanic island in the Windward Isles (2,5)'" .)