Narrow strip of land (7)
I believe the answer is:
isthmus
'narrow strip of land' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for isthmus that I've seen before include "Narrow land bridge" , "Narrow strip of land in sea" , "Neck of land connecting larger areas" , "Narrow strip of land with water on two sides" , "Narrow strip of land between two larger ones" .)