Great multitude (4)
'great multitude' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for host that I've seen before include "Does he invite a large number?" , "One entertains guests" , "Provide entertainment" , "lot of people" , "Party giver" .)
(Other definitions for myriad that I've seen before include "Immense number found by dim ray" , "A great number" , "Lots of" , "Large indefinite number" , "Too numerous to be counted" .)