Lecture successful business student enters at the end (7)

I believe the answer is:
lambast
'lecture' is the definition.
The definition and answer can be both to do with communicating as well as being verbs in their base form.
Perhaps they are linked in a way I don't understand?
'successful business student enters at the end' is the wordplay.
'successful business student' becomes 'mba' (I can't explain this - if you can you should give a lot more credence to this answer).
'enters' means one lot of letters goes inside another.
'at the end' becomes 'last' (I've seen this in another clue).
'mba' inserted into 'last' is 'LAMBAST'.
Can you help me to learn more?
(Other definitions for lambast that I've seen before include "Reprimand" , "Bash" , "Beat severely" , "Berate" , "rubbish" .)
