Stone dealer maybe accepts million (7)
I believe the answer is:
emerald
'stone' is the definition.
(type of gemstone)
'dealer maybe accepts million' is the wordplay.
'maybe' indicates anagramming the letters.
'accepts' indicates putting letters inside.
'million' becomes 'm' (abbreviation).
'dealer' anagrammed gives 'eerald'.
'eerald' enclosing 'm' is 'EMERALD'.
(Other definitions for emerald that I've seen before include "...re medal? (Anag)" , "Gem associated with Ireland" , "La couleur" , "Green - jewel" , "Gem; type of moth" .)