Related Clues:

• Existing but not yet active or visible
• Unused or novel
• Existing but not yet developed, say ability
• Existing but not yet active or developed
• Fresh, unused
• Existing but not yet active
• Not yet visible or developed
• Existing but not yet developed or active
• Hidden, undeveloped
• 'Fresh, novel (3)'
• 'Hidden, undeveloped (6)'
• Potential not realised
• This might insist, by the sound of it, on a turn of what is not the start of 9 across
• Not old enough to swell up?
• It's just waiting to be brought out and pitched after half a century