Possible Clues:

• Triple play, for one
• 'Something unusual, perhaps collectable (6)'
• How unusual that I try to get back the start of 9 across
• Diamond value factor
• Seldom-seen thing
• Unusual thing for artist regularly absorbed by fish
• It's tipped in the object of an old Irish joke, and it doesn't happen very often!
• It's unusual to try to get around the air
• To be an unusual Academician I try
• A very unusual thing