Choral piece: leave with line in song rising (6)
I believe the answer is:
gloria
'choral piece' is the definition.
The definition suggests a singular noun which matches the answer.
'leave with line in song rising' is the wordplay.
'leave with' becomes 'go' (to go is to depart or leave. I am not sure about the 'with' bit.).
'line' becomes 'l' (used when specifying particular lines from a poem).
'in' indicates putting letters inside.
'song' becomes 'air' (air can mean a piece of music).
'rising' says the letters should be written in reverse (letters written upwards in a down clue).
'air' reversed gives 'ria'.
'go' enclosing 'l' is 'glo'.
'glo'+'ria'='GLORIA'
Can you help me to learn more?
(Other definitions for gloria that I've seen before include "Portion of Mass" , "Woman" , "-- Gaynor, disco diva" , "Prayer: '... in excelsis Deo'" , "contribution to mass production" .)