Musical instruments vital to life (6)
I believe the answer is:
organs
'musical instruments' is the definition.
(organ is a kind of musical instrument)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for organs that I've seen before include "Functional parts of the body, or musical instruments" , "Heart and lungs are vital ones" , "newspapers" , "Functional units in the body" , "Groans over distinct parts of animal body" .)