Emperor's granny concealing Eastern European origins, originally (8)
I believe the answer is:
napoleon
'emperor's' is the definition.
(Napoleon is an example)
'granny concealing eastern european origins originally' is the wordplay.
'granny' becomes 'nan'.
'concealing' indicates putting letters inside.
'eastern european' becomes 'pole'.
'origins' suggests taking the first letters.
The initial letter of 'originally' is 'o'.
'pole'+'o'='poleo'
'nan' enclosing 'poleo' is 'NAPOLEON'.
(Other definitions for napoleon that I've seen before include "Cake" , "Open loan to the French general. strangely" , "The little French general" , "Emperor - brandy" , "Ex-dictator" .)