Brown as pie mixture (5)
I believe the answer is:
sepia
'brown' is the definition.
(I know that sepia is a type of brown)
'as pie mixture' is the wordplay.
'mixture' is an anagram indicator.
'as'+'pie'='aspie'
'aspie' anagrammed gives 'SEPIA'.
(Other definitions for sepia that I've seen before include "Colour of old photographs" , "Sort of drawing" , "Brown with a red tinge" , "brownish colour" , "Old drawing" .)