Land yielding rare tin (7)
I believe the answer is:
terrain
'land' is the definition.
(terrain is land or territory)
'yielding rare tin' is the wordplay.
'yielding' indicates an anagram.
'rare'+'tin'='raretin'
'raretin' anagrammed gives 'TERRAIN'.
(Other definitions for terrain that I've seen before include "Land (viewed tactically)" , "Stretch of land, emphasising natural features" , "Landscape" , "Piece of ground" , "Tract of land with prevailing characteristic" .)