Land on an isthmus (6)
I believe the answer is:
panama
'land on an isthmus' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for panama that I've seen before include "What may be seen overhead" , "'Country, canal and hat (6)'" , "Wide-brimmed hat" , "Criticise" , "country divided by boaters?" .)