Small piece of land in narrow strip of water, north to south (5)
I believe the answer is:
islet
'small piece of land' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for islet that I've seen before include "Detached bit of land" , "Small piece of land surrounded by water" , "Piece of land in e.g. river" , "small key?" , "Cay, for example" .)