For one German hosting buffet it helps to make omelette (9)
I believe the answer is:
'it helps to make omelette' is the definition.
(device for beating an egg)
'for one german hosting buffet' is the wordplay.
'for one' becomes 'eg' (both can mean 'for example').
'german' becomes 'ger' (abbreviation).
'hosting' is an insertion indicator.
'buffet' becomes 'beat' (I've seen this before).
'ger' going around 'beat' is 'gbeater'.
(Other definitions for eggbeater that I've seen before include "Meringue maker's tool" , "Whisk" , "Kitchen gizmo" , "Kitchen utensil" .)