A tin hat I designed for islander (8)
I believe the answer is:
tahitian
'islander' is the definition.
(I've seen this before)
'a tin hat i designed' is the wordplay.
'designed' is an anagram indicator (designed with the letters).
'a'+'tin'+'hat'+'i'='atinhati'
'atinhati' with letters rearranged gives 'TAHITIAN'.
'for' acts as a link.
(Other definitions for tahitian that I've seen before include "Native of South Pacific island, capital Papeete" , "It, in a hat (anag)" , "inhabitant of island" , "South Sea islander" , "someone on tropic island" .)