Campaigner having a certain appeal in more basic setting (8)
I believe the answer is:
crusader
'campaigner' is the definition.
(eg someone on a moral crusade)
'a certain appeal in more basic setting' is the wordplay.
'a certain appeal' becomes 'SA' (sex appeal).
'in' indicates putting letters inside.
'more basic setting' becomes 'cruder' (I can't justify this - if you can you should believe this answer much more).
'sa' going into 'cruder' is 'CRUSADER'.
'having' acts as a link.
Can you help me to learn more?
(Other definitions for crusader that I've seen before include "For example, Richard I" , "Campaigner for a cause, like Richard the Lionheart" , "religious zealot" , "Medieval expeditionary" , "Christian warrior" .)