When unmarried, in some need (3)
I believe the answer is:
nee
'when unmarried in' is the definition.
Both the definition and answer are adjectives. Perhaps you can see a link between them that I can't see?
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for nee that I've seen before include "It indicates a married woman's single name" , "Born (to indicate maiden name)" , "Born (indicating a woman's maiden name)" , "Prefix indicating maiden name of married woman" , "Prefix indicating maiden name before marriage" .)