Island 2 keeping key (5)
I believe the answer is:
malta
'island' is the definition.
(I know that Malta is a island)
'2 keeping key' is the wordplay.
'a' becomes 'ma' (I can't explain this - if you can you should believe this answer much more).
'keeping' indicates putting letters inside.
'key' becomes 'alt' (the Alt keyboard button).
'ma' going around 'alt' is 'MALTA'.
(Other definitions for malta that I've seen before include "Island European country" , "small island" , "defiant island in WW2" , "Island member of the European Union" , "Island to the south of Sicily" .)