They entertain vast crowds (5)
I believe the answer is:
hosts
This clue is a double definition.
'they entertain' is the first definition.
(I've seen this before)
'vast crowds' is the second definition.
(I've seen this before)
(Other definitions for hosts that I've seen before include "Multitudes" , "welcomers of guests" , "Landlords" , "Those giving a party" , "Shots fired at party givers" .)