Very small land mass (5)
I believe the answer is:
islet
'very small land mass' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for islet that I've seen before include "Tiles to make a small island" , "named after Langerhans?" , "One of Langerhans's" , "Ait or key" , "Tiles (anag.)" .)