Related Clues:

• Purify or improve
• Filter or process as with oil
• Elucidate, make clear
• Remove impurities or make cultured
• Elucidate, clarify
• Get rid of impurities
• Does this show how once it was flat land?
• If it was formerly clear of mountains, is that what makes it clear?
• Not to make it crude, that's about what you have to pay
• Too old to look at the river, by the sound of it
• Does this tell you why this was formerly so flat?
• Make one pay a second time? That'll make one purer
• It will make it more pure to have it on the swimmer in the lough
• Purely to make one pay the penalty all over again (6)
• Make it clear, this former clear space