Turnover, spectacular at first, is contained by Pacific island (6)
I believe the answer is:
samosa
'turnover' is the definition.
(samosa is a type of spicy turnover)
'spectacular at first is contained by pacific island' is the wordplay.
'at first' suggests taking the first letters.
'is contained by' means one lot of letters goes inside another.
'pacific island' becomes 'samoa' (I've seen this in another clue).
The first letter of 'spectacular' is 's'.
's' going inside 'samoa' is 'SAMOSA'.
(Other definitions for samosa that I've seen before include "Small Indian turnover, fried and served hot" , "Indian fried pastry" , "Triangular Indian turnover" , "Grub from India" , "Indian dish" .)