Possible Clues:

• Social problem
• It's not forward that one would start to throw this
• Reluctance to throw over the head
• Reserve withdrawn by leaders of northern English summer school
• Cast head as reserve
• Toss the head, showing a lack of confidence
• Cause of some blushing
• Shrinking violet's problem
• Bashful's quality attempt to hit head
• Toss head in demonstration of reticence