Related Clues:

• Playing hard-to-get
• Not open
• Overly compliant
• Playfully shy
• Lacking courage
• Far from a drama queen
• Earth's heirs?
• Not quite enough
• Averse to first moves, e.g.
• Not made of brass
• Like many a wallflower
• Tractable
• Not outgoing
• Reluctant to elucidate
• Staid