Contralto’s ending, say, in lower part of duet (7)
I believe the answer is:
secondo
'lower part of duet' is the definition.
(lower part of a musical duet)
I cannot understand how the remainder of the clue works.
(Other definitions for secondo that I've seen before include "Musical" , "Work hands perform" , "participant in piano duet?" , "Part played by duettist" , "lower part" .)