Chorister's big moment (4)
I believe the answer is:
solo
'chorister's big moment' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for solo that I've seen before include "Type of whist" , "something for one to do" , "Unaccompanied - card game" , "On one's own, unaccompanied" , "Performed by a single voice or instrument" .)