Possible Clues:

• Rigidness or strictness
• Austerity that's new in author's son
• The state of being harsh and severe
• Grimly serious quality
• Severity not in the bows to start with
• Southern bird over promontory - serious nature!
• Austerity
• Strictly speaking, this might have nothing to do with the bow
• Back Head to show severity
• Back head of uncompromising nature