### Clue: across Stink in so much holy mess with setters' lack of sophistication (9,6)
### Answer: SCHOOLBOY HUMOUR 
 ### Explanation: Definition: lack of sophistication
 B.O.(abbrev. for "body odour";a stink from an unwashed body) **contained in**(in) **anagram of**(… mess) SO MUCH HOLY **plus**(with) OUR(possessive pronoun of "setters", self-referentially).