Posh theologian visiting landed earl, originally a protester (7)
I believe the answer is:
luddite
'a protester' is the definition.
(19th-century anti-industrialisation protestor)
'posh theologian visiting landed earl originally' is the wordplay.
'posh' becomes 'u' (abbreviation for upper-class - opposite to non-U).
'theologian' becomes 'dd' (Doctor of Divinity degree).
'visiting' means one lot of letters goes inside another.
'landed' becomes 'lit' (I've seen this in another clue).
'originally' indicates taking the first letters.
The initial letter of 'earl' is 'e'.
'u'+'dd'='udd'
'udd' placed within 'lit' is 'luddit'.
'luddit'+'e'='LUDDITE'
(Other definitions for luddite that I've seen before include "Mechanisation resister" , "Opponent of technological progress" , "Opponent of modern technology" , "Early nineteenth century anti-machinery demonstrator" , "Diluted by opposer of new technology" .)