Primarily the ultimate tune to invigorate, performed by the whole orchestra (5)
I believe the answer is:
tutti
'performed by the whole orchestra' is the definition.
I can't tell whether this defines the answer.
'primarily the ultimate tune to invigorate' is the wordplay.
'primarily' indicates taking the first letters.
The first letters of 'the ultimate tune to invigorate' is 'TUTTI'.
Can you help me to learn more?
(Other definitions for tutti that I've seen before include "Passage using all instruments" , "Section for all musicians" , "All (stage direction)" , "All instruments must play" , "(Of an orchestra) all to play together" .)