Crossbred, of mixed ancestry (6)
I believe the answer is:
hybrid
I believe this clue is a double definition.
'crossbred' is the first definition.
(similar in meaning)
'of mixed ancestry' is the second definition.
(I've seen this before)
(Other definitions for hybrid that I've seen before include "Cross breed" , "Genetic cross" , "Cross of two different species or varieties" , "Plant that is the offspring of two different species" , "Like a mule" .)