Totalitarian leader, Republican, in deep trouble (3,7)
I believe the answer is:
big brother
'totalitarian leader' is the definition.
(leader in the novel Nineteen Eighty-Four)
'republican in deep trouble' is the wordplay.
'republican' becomes 'r' (abbreviation).
'in' means one lot of letters goes inside another.
'deep' becomes 'big' (both can mean profound or intense).
'trouble' becomes 'bother' (synonyms).
'big'+'bother'='bigbother'
'r' inserted into 'bigbother' is 'BIG BROTHER'.
(Other definitions for big brother that I've seen before include "Exerciser of total control over people's lives" , "Orwellian dictator - TV show" , "Orwell's head of state in "Nineteen Eighty-four"" , "TV show - dictatorial leader" , "One keeping watch" .)