Sharp edges taken off stone slab (4)
I believe the answer is:
able
'sharp' is the definition.
(thesaurus)
'edges taken off stone slab' is the wordplay.
'edges taken off' indicates the central letters (letters at the edges are removed).
'stone slab' becomes 'tablet' (stone tablet).
The middle letters of 'tablet' are 'ABLE'.
(Other definitions for able that I've seen before include "Practised" , "Competent, capable" , "Competent, having ability" , "Gifted" , "Fully competent" .)