Historian, atrocious lecturer with hesitant expression (10)
I believe the answer is:
chronicler
'historian' is the definition.
(chronicler is a kind of historian)
'atrocious lecturer with hesitant expression' is the wordplay.
'atrocious' becomes 'chronic' (I can't explain this - if you can you should give a lot more credence to this answer).
'lecturer' becomes 'l'.
'with' is a charade indicator (letters next to each other).
'hesitant expression' becomes 'er'.
'chronic'+'l'+'er'='CHRONICLER'
Can you help me to learn more?
(Other definitions for chronicler that I've seen before include "I make history" , "Historian" , "16 dn of history" , "One who records important events" .)