Related Clues:

• Subtlety, obvious one
• Subtle quality in finished counterfeit note
• Subtle extra meaning
• Secondary quality
• Subtle quality, or unsubtle one?
• It's obvious one will make a suggestion
• Manifest single part of harmonic series
• A hint - plain one!
• Hint that's a blatant one
• Subtle meaning - but also an obvious one
• Making plain to one by innuendo
• Nuance obvious to an individual
• Open with a number that is suggestive
• Harmonic apparent on single
• Obvious -- only a suggestion