Stone dealer crazy to accept thousand (7)
I believe the answer is:
emerald
'stone' is the definition.
(type of gemstone)
'dealer crazy to accept thousand' is the wordplay.
'crazy' indicates an anagram.
'to accept' indicates putting letters inside.
'thousand' becomes 'm' (Roman numeral for a thousand).
'dealer' with letters rearranged gives 'eerald'.
'eerald' placed around 'm' is 'EMERALD'.
(Other definitions for emerald that I've seen before include "La couleur" , "Green - jewel" , "Precious gemstone" , "Gem; type of moth" , "Mere lad (anag.)" .)