Possible Clues:

• Be mean, as troublemaker sitting at back of teachers' room
• Be thrifty and parsimonious
• Save millions in abridged text
• Little person stays cold, not hot, to make economies
• Senior common room is most profligate first of all — economise
• Short text about Mike's stint
• Save carefully, reducing irresponsibly made purchases initially
• Save son caught parking on edge
• Economise seconds before squeeze?
• Be very economical, as Surrey's opener's at crease