Youngster brought to a Caribbean island (4)
I believe the answer is:
Here is my best explanation:
'caribbean island' is the definition.
(I've seen this before)
'youngster brought to a' is the subsidiary indication.
'youngster' becomes 'cub' (I've seen this in other clues**).
'brought to' says to put letters next to each other.
(Other definitions for cuba that I've seen before include "Island S. of Florida", "A Caribbean republic", "Castro's country", "Largest West Indies island", "Castro's isle", "West Indian island", "Large Caribbean island", "Hemingway's stamping-ground", "Its capital is Havana" and "detached area".)