Port-of-Spain's island (8)
I believe the answer is:
trinidad
'port-of-spain's island' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for trinidad that I've seen before include "West Indies island" , "... [WI ISLAND]" , "Port of Spain island" , "West Indian island paired with Tobago" , "English-speaking island off Venezuela" .)