Dictator's address cut short in error (6)
I believe the answer is:
stalin
'dictator's' is the definition.
(USSR leader Joseph Stalin)
'address cut short in error' is the wordplay.
'address' becomes 'talk' (both can mean a formal speech or presentation).
'cut short' means to remove the last letter.
'in' is an insertion indicator.
'error' becomes 'sin' (I've seen this before).
'talk' with its final letter taken away is 'tal'.
'tal' put within 'sin' is 'STALIN'.
(Other definitions for stalin that I've seen before include "Joseph -, Russian World War two dictator" , "Tyrant - last in (anag)" , "Lenin's successor" , "Dread dictator among Latins" , "Former USSR leader" .)