Vocalist’s numbers lock (10)
I believe the answer is:
songstress
'vocalist's' is the definition.
(songstress is a kind of vocalist)
'numbers lock' is the wordplay.
'numbers' becomes 'songs' (I can't explain this - if you can you should give a lot more credence to this answer).
'lock' becomes 'tress' (I've seen this before).
'songs'+'tress'='SONGSTRESS'
Can you help me to learn more?
(Other definitions for songstress that I've seen before include "performer" , "Female singer" , "coloratura perhaps" , "Woman making up the numbers" , "Soprano perhaps" .)