Valiant choir somehow held a note (6)
I believe the answer is:
'valiant' is the definition.
(I've seen this before)
'choir somehow held a note' is the wordplay.
'somehow' is an anagram indicator.
'held' indicates putting letters inside.
'a note' becomes 'e' (musical note).
'choir' with letters rearranged gives 'hroic'.
'hroic' going around 'e' is 'HEROIC'.
(Other definitions for heroic that I've seen before include "Supremely courageous and brave" , "Dramatic" , "Courageous - daring" , "Of deed or person, very brave" , "Gallant" .)