A large number of staff eaten by big cat from the east (8)
I believe the answer is:
regiment
'a large number' is the definition.
'staff eaten by big cat from the east' is the wordplay.
'staff' becomes 'men' (I've seen this in other clues).
'eaten by' means one lot of letters goes inside another.
'big cat' becomes 'tiger' (tiger is a kind of big cat).
'from the east' is a reversal indicator.
'tiger' back-to-front is 'regit'.
'men' inserted into 'regit' is 'REGIMENT'.
'of' acts as a link.
(Other definitions for regiment that I've seen before include "The Grenadier Guards, for example" , "subject to excessive control" , "Order" , "Military unit" , "Section of an army" .)