Possible Clues:

• High and low phenomena
• Holds, with 'over'
• Those fluctuating in time - beware of them
• Mainly ups and downs found in features editor's returns
• Current trends in fashionable diets
• Edits (anag.)
• They occur daily, i.e. when fully rearranged
• Periodic changes in sea levels
• Links across Germany offering daily highs and lows
• Surfer's concern