mephisto

[genius55]

stuck at bottom left
continue most recent model (4)

heckles speaker's introduction without provacation (8)

the head's less ambitious students (4)
thanx

[sarumite]

1. Continue = " Last " = Most Recent.

[kayakamina]

No ll

[kettledrum]

needless

[Quizmonster]

'Poll' rather than 'noll' is, I think, the answer to the 'head' clue. The second meaning of 'poll' in Chambers reads: "(Old Cambridge University slang)) n. the body of students who did not seek or obtain honours; a pass degree."
They would certainly better fit the "less ambitious students" part of the clue than 'noll'.
(Sorry, K!)

[genius55]

Thanks very much guys and for the explanation Quizmonster. I shall attack the rest anew tonight.