Sound organ composition (5)
I believe the answer is:
groan
'sound' is the definition.
(I have seen 'Sound of despair ' mean 'groan' so perhaps 'sound' could also mean 'groan')
'organ composition' is the wordplay.
'composition' is an anagram indicator (letters arranged or composed in a different order).
'organ' is an anagram of 'GROAN'.
(Other definitions for groan that I've seen before include "Complain" , "Express disappointment, pain" , "Complaint" , "Titus -- (Mervyn Peake)" , "See 18 Down" .)