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