Ends up in a narrow tongue of land (4)
I believe the answer is:
spit
'a narrow tongue of land' is the definition.
(spit can mean a projecting piece of land)
'ends up' is the wordplay.
'ends' becomes 'tips' (the tips of something are its ends).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'tips' backwards is 'SPIT'.
'in' is the link.
(Other definitions for spit that I've seen before include "Ancient Mount Parnassus city" , "Expectorate into pits" , "Sand bar" , "Narrow strip of land projecting into the sea" , "Be furious" .)