Mix, combine (5)
I believe the answer is:
blend
I believe this is a double definition.
'mix' is the first definition.
(I know that mix can be written as blend)
'combine' is the second definition.
(I know that combine can be written as blend)
(Other definitions for blend that I've seen before include "Fusion" , "Thorough mixture" , "Intermix" , "Coalesce" , "Mix together" .)