Mean people hide stones (10)
I believe the answer is:
skinflints
'mean people' is the definition.
(mean or miserly people)
'hide stones' is the wordplay.
'hide' becomes 'skin' (a hide is an animal skin).
'stones' becomes 'flints' (I've seen this before).
'skin'+'flints'='SKINFLINTS'
(Other definitions for skinflints that I've seen before include "Near ones" , "Cheapskates" , "near people" .)