Possible Clues:

• Teach new skills
• Prepare for new job in novel terrain
• Terrain (anag.)
• Teach new skills to soldiers' column
• Teach fresh skills
• Keep going over one of the basics in school again
• Go in for further education, respecting coaches
• Give new instruction - check about skill that's picked up
• Study for new job and check about retrospective art
• School again has to keep detaining Rex