Cross at cast shunning birthday working (6)
I believe the answer is:
hybrid
'cross' is the definition.
(I've seen this in another clue)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for hybrid that I've seen before include "Offspring of two different species or varieties" , "Compound, mixture" , "Genetic cross" , "Crossed offspring" , "Amalgam" .)