Hosts banquets, taking quick look round inside — Duke's not there! (10)
I believe the answer is:
innkeepers
'hosts' is the definition.
('innkeeper' can be a synonym of 'host')
I don't understand the remainder of the clue.
(Other definitions for innkeepers that I've seen before include "They entertain" , "Publicans" , "Hosts" , "Landlords" , "Taverners" .)