Harangue one leaving employment ... (5)
I believe the answer is:
trade
'employment' is the definition.
(thesaurus)
'harangue one leaving' is the wordplay.
'harangue' becomes 'tirade' (I've seen this before).
'one' becomes 'i' (Roman numeral).
'leaving' suggests deleting specific letters.
'tirade' with 'i' taken out is 'TRADE'.
(Other definitions for trade that I've seen before include "Personal occupation" , "groundsman?" , "Business - (kind of) wind" , "Commercial dealings" , "Give and receive (blows)" .)