Spare girl? (5)
I believe the answer is:
sylph
'spare girl?' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps there's a link between them I don't understand?
This is the entire clue.
Can you help me to learn more?
(Other definitions for sylph that I've seen before include "Imaginary spirit of the air" , "Slender, graceful girl" , "Slim person" , "Graceful lass" , "Slim female" .)