Island tree, by the sound of it (6)
I believe the answer is:
cyprus
'island' is the definition.
(Cyprus is an island)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for cyprus that I've seen before include "Mediterranean isle" , "Mediterranean island of Aphrodite" , "Othello island" , "Large East Mediterranean island" , "Aphrodite's island" .)