Seafood terror on island (6)
I believe the answer is:
scampi
'seafood' is the definition.
(I've seen this before)
'terror on island' is the wordplay.
'terror' becomes 'scamp' (both can mean a naughty child).
'on' says to put letters next to each other.
'island' becomes 'i'.
'scamp'+'i'='SCAMPI'
(Other definitions for scampi that I've seen before include "Dish of fried shrimp or prawns" , "Large prawns cooked in batter" , "Dish of cooked shrimps or prawns" , "Shellfish" , "Cooked Norway lobster" .)