Teacher with English class not entirely doomed (4,3)
I believe the answer is:
done for
'doomed' is the definition.
(I've seen this in another clue)
'teacher with english class not entirely' is the wordplay.
'teacher' becomes 'don' (don can mean an academic - especially at Oxbridge).
'with' says to put letters next to each other.
'english' becomes 'E' (abbreviation as in OED).
'class' becomes 'form' (form class is a kind of class).
'not entirely' means to remove the last letter (not all of the word).
'form' with its last letter taken away is 'for'.
'don'+'e'+'for'='DONE FOR'
(Other definitions for done for that I've seen before include "Sunk" , "in serious trouble" , "finished" , "condemned" , "killed" .)