Black boxer comes to island (4)
I believe the answer is:
bali
'island' is the definition.
(Indonesian island)
'black boxer comes to' is the wordplay.
'black' becomes 'b' (as in pencil classifications).
'boxer' becomes 'ali' (Muhammad Ali).
'comes to' is a charade indicator (letters next to each other).
'b'+'ali'='BALI'
(Other definitions for bali that I've seen before include "mountainous island" , "Island in Indonesia" , "Holiday island to the east of Java" , "Indonesian island, east of Java" , "Indonesian holiday destination" .)