It's capital as a sun resort (6)
I believe the answer is:
nassau
'it's capital' is the definition.
(capital of the Bahamas)
'as a sun resort' is the wordplay.
'resort' indicates anagramming the letters (re-sort the letters).
'as'+'a'+'sun'='asasun'
'asasun' anagrammed gives 'NASSAU'.
(Other definitions for nassau that I've seen before include "Dublin street in the Bahamas?" , "Bahamas cap." , "Capital of the Bahamas" , "city" , "Port of the Bahamas" .)