Possible Clues:

• Show-off's exploits may secure low grades for pupils
• Exploits covering half-nude novices?
• Pupils or apprentices
• Sent dust to those who learn
• Shock mostly has an adverse effect on learners
• They look to 18 across and are written about in 14 across
• Journalist about to probe rag events and those who organise them?
• Fundamentalists ignore fan mail from those in school
• They have class
• Trainees boss sent first to the base