You'd be unlucky to lose yours (5)
I believe the answer is:
shirt
'you'd' is the definition.
Both the definition and answer are singular nouns.
Perhaps there's an association between them I don't understand?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for shirt that I've seen before include "Man's garment" , "tailored garment" , "Garment for upper male body, usually cotton" , "One may lose it at the bookie's" , "Male garment worn with tie" .)