Very obviously calling, and loud always initially? (5)
I believe the answer is:
vocal
'very' is the definition.
Both the answer and definition are adjectives. Perhaps there's a link between them I don't understand?
I can't explain the rest of the clue.
(Other definitions for vocal that I've seen before include "Forthright in argument" , "speaking loudly" , "not instrumental" , "To do with the voice, say cords" , "Outspoken (e.g. criticism)" .)