Salvation Army taken in by more rough-and-ready evangelist? (8)
I believe the answer is:
crusader
'evangelist?' is the definition.
(someone on a religious crusade)
'salvation army taken in by more rough-and-ready' is the wordplay.
'salvation army' becomes 'SA' (abbreviation).
'taken in by' indicates putting letters inside.
'more rough-and-ready' becomes 'cruder' (rough-and-ready means crude or basic).
'sa' placed into 'cruder' is 'CRUSADER'.
(Other definitions for crusader that I've seen before include "Person engaged upon a cause" , "Medieval fighter for the Holy Land" , "Campaigner -- rude scar (anag)" , "Advocate for a cause - rude scar (anag)" , "Medieval expeditionary" .)