Protester did wrong breaking into vehicle behind back of school (7)
I believe the answer is:
luddite
'protester' is the definition.
(19th-century anti-industrialisation protestor)
'did wrong breaking into vehicle behind back of school' is the wordplay.
'wrong' indicates an anagram.
'breaking into' is an insertion indicator.
'vehicle' becomes 'ute' (Australian abbreviation for utility vehicle).
'behind' is a charade indicator (letters next to each other).
'back of' says to take the final letters.
The last letter of 'school' is 'l'.
'did' is an anagram of 'ddi'.
'ddi' inserted inside 'ute' is 'uddite'.
'uddite' put after 'l' is 'LUDDITE'.
(Other definitions for luddite that I've seen before include "Diluted by opposer of new technology" , "Opponent of technological progress" , "One resisting technology progress" , "Diluted for old machinery wrecker" , "Worker who opposed mechanisation" .)