Mixture concocted by Meg Lane (7)
I believe the answer is:
melange
'mixture' is the definition.
(I know that melange is a type of mixture)
'concocted by meg lane' is the wordplay.
'concocted' indicates anagramming the letters.
'by' means one lot of letters go next to another.
'meg' put after 'lane' is 'lanemeg'.
'lanemeg' anagrammed gives 'MELANGE'.
(Other definitions for melange that I've seen before include "Mixed bag" , "A French blend or mixture" , "Miscellany" , "Gallimaufry" , "Medley" .)