That guy's greetings (3)
I believe the answer is:
his
'greetings' is the definition.
(more than one hi)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for his that I've seen before include "That man's" , "that chap's" , "To - Coy Mistress (Marvell)" , "It belongs to him" , "Belonging to the male" .)