Rebuke cruel and extremely terse cook (7)
I believe the answer is:
lecture
'rebuke' is the definition.
(lecture is a kind of rebuke)
'cruel and extremely terse cook' is the wordplay.
'and' is a charade indicator (letters next to each other).
'extremely' suggests removing the centre (only the extremes of the word are used).
'cook' indicates anagramming the letters.
'terse' with its centre taken out is 'te'.
'cruel' put after 'te' is 'tecruel'.
'tecruel' with letters rearranged gives 'LECTURE'.
(Other definitions for lecture that I've seen before include "Discourse for students" , "An instructive talk, in school or church" , "Formal lesson" , "Talk; reprimand" , "University teaching period" .)