Sound conveyed by historic languages (5)
I believe the answer is:
clang
'sound' is the definition.
(clang is a kind of sound)
'conveyed by historic languages' is the wordplay.
'conveyed by' indicates a hidden word.
'CLANG' is hidden in the letters of 'historic languages'.
(Other definitions for clang that I've seen before include "Make a loud metallic noise" , "Dull sound of a bell" , "Noise as of cymbals" , "Harsh cry" , "Resounding effect" .)