Burst of applause (5)
I believe the answer is:
'burst of applause' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for salvo that I've seen before include "Fusillade, volley" , "Unusual excuse" , "Simultaneous discharge of artillery" , "Outburst, as of applause" , "Barrage" .)