Such unions aren't recognised (8)
I believe the answer is:
bigamous
'such' is the definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for bigamous that I've seen before include "Underground cemetery" , "not right to have such a marriage?" , "Legal description of a marriage to a person while legally married to another" , "Marrying twice illegally" , "Having another other half!" .)