She sings in a register below various other choir leaders (8)
I believe the answer is:
vocalist
'she sings' is the definition.
I can't tell whether this definition defines the answer.
'a register below various other choir leaders' is the wordplay.
'register' becomes 'list' (listing is a kind of registering).
'below' says to put letters next to each other (in a down clue, some letters go below others).
'leaders' says to take the initial letters.
The first letters of 'various other choir' is 'voc'.
'a'+'list'='alist'
'alist' after 'voc' is 'VOCALIST'.
'in' acts as a link.
Can you help me to learn more?
(Another definition for vocalist that I've seen is " Singer with a pop group".)