Possible Clues:

• Female serving the school
• Her dispensing work might be in a mess
• School lunch server
• School supervisor finds two of academy's fourth years concealing secret note
• Initially dubious, target peeress's job in school
• Spooner perhaps led dray shakily outside pub
• Adult female attending courses at school
• School meals server
• Noise as a geek secures the cross-channel server
• Extremely dicey, admitting boy to private school she works at