Related Clues:

• The North can only produce this synthetically
• This will catch up with the start of 8 down
• One over nine from behind without reduction
• How one might catch up with double figures
• Being synthetic, it's made of only Nitrogen
• A thread of water all around it at last
• The North gets what's only all synthetic
• The catch in this is that it's back for double figures
• There may be a catch, an many a hole, in this price (3)
• How the North is only synthetic
• There's a catch in it - that's the price for you
• The North is only twisted to a material extent
• For 1 down one's number is up
• The catch in this is that it's a back number
• This will catch X back