Java product, perhaps filling island cocktail (9)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

APP (Java product, perhaps), LET IN (filling), I (island) . APPLET (Java product, perhaps), IN (filling), I (island). This was the clue that did for me. I never heard of the cocktail; nor have Chambers Word Wizard or  Crossword Solver. Thanks to glh for the correction to my original parsing.