Howdy! (5)
'howdy' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for hello that I've seen before include "A salutation" , "glossy magazine" , "Conventional word of greeting" , "Greeting - celebrity magazine" , "Introductory greeting" .)
(Other definitions for hey that I've seen before include "Exclamation to call attention" , "Exclamation calling attention" , "Call attracting attention" .)