Certain Army member firing all guns (5)
I believe the answer is:
salvo
'certain army' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for salvo that I've seen before include "Round of fire" , "Outburst, as of applause" , "Simultaneous burst of gunfire" , "Burst (of applause, insults, artillery etc)" , "What comes across" .)