Loud greeting uttered (4)
I believe the answer is:
high
'loud' is the definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?
'greeting uttered' is the wordplay.
'greeting' becomes 'hi' (hi is a kind of greeting).
'uttered' shows a homophone (sound like).
'hi' is a homophone of 'HIGH'.
Can you help me to learn more?
(Other definitions for high that I've seen before include "Relatively great or specific elevation" , "Great in rank" , "Outstanding feature" , "having senior ranking?" , "American school" .)