Formal greeting (4)
I believe the answer is:
hail
'formal greeting' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for hail that I've seen before include "Welcome - cold shower" , "Greet, acclaim" , "Call for - praise, vociferously" , "Greeting - falling stones" , "Ave - it's frozen rain" .)