Dot in the ocean (5)
I believe the answer is:
islet
'dot in the ocean' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for islet that I've seen before include "named after Langerhans?" , "Ait or eyot" , "detached territories?" , "A small piece of territory" , "Eyot, key" .)