Island, one south of hot country (5)
I believe the answer is:
haiti
'island' is the definition.
(Haiti is an example)
'one south of hot country' is the wordplay.
'one' becomes 'i' (Roman numeral).
'south of' says to put letters next to each other (in a down clue, some letters go under others).
'hot country' becomes 'hait' (I can't justify this - if you can you should believe this answer much more).
'i' put after 'hait' is 'HAITI'.
Can you help me to learn more?
(Other definitions for haiti that I've seen before include "Republic sharing WI isle" , "one in the Caribbean" , "West Indian country, capital Port-au-Prince" , "West Indies republic" , "West part of Hispaniola" .)