Plateau's kin (4)
I believe the answer is:
mesa
'plateau's kin' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for mesa that I've seen before include "Flat tableland with steep edges" , "Flat tableland with steep sides" , "Flat-topped hill with steep sides, common in the southwestern US" , "Geographical feature" , "In the USA, a steep-sided flat-topped hill" .)