Declare invalid, as a marriage (5)
I believe the answer is:
annul
(Other definitions for annul that I've seen before include "Render invalid" , "Nullify" , "Cancel, revoke" , "Invalidate" , "Countermand" .)
I believe the answer is:
annul
(Other definitions for annul that I've seen before include "Render invalid" , "Nullify" , "Cancel, revoke" , "Invalidate" , "Countermand" .)