Might worried, religious sister lament the break-up? (9)
I believe the answer is:
annulment
'might' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for annulment that I've seen before include "recall" , "cancellation" , "dissolution" , "Countermand" , "Declaration of invalidity, of a marriage say" .)