Turned up collar, punching a teacher in scrap (7)
I believe the answer is:
abandon
'scrap' is the definition.
(I've seen this before)
'turned up collar punching a teacher' is the wordplay.
'turned up' is a reversal indicator.
'collar' becomes 'nab' (both can mean to catch a person).
'punching' indicates putting letters inside (I've seen this in other clues).
'teacher' becomes 'don' (don is a kind of teacher).
'nab' backwards is 'ban'.
'a'+'don'='adon'
'ban' going inside 'adon' is 'ABANDON'.
'in' acts as a link.
(Other definitions for abandon that I've seen before include "Kick" , "Czech city" , "Wantonness: desert" , "Walk out on" , "Forsake, leave behind" .)