Feature no vocal composition (7)
I believe the answer is:
volcano
'feature' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'no vocal composition' is the wordplay.
'composition' indicates anagramming the letters (letters arranged or composed in a different order).
'no'+'vocal'='novocal'
'novocal' with letters rearranged gives 'VOLCANO'.
Can you help me to learn more?
(Other definitions for volcano that I've seen before include "Opening in earth's crust ejecting molten matter" , "kind of mountain" , "Dormant or active mountain" , "Scene of eruptions" , "Fiery mountain" .)