Possible Clues:

• It's tough not replacing it in central fund
• Tricky to negotiate -- like a reef?
• Piece of work, not typically difficult
• Complicated, like a sandpiper?
• Tricky, describing wading bird?
• Difficult being tied up?
• Tricky (to untangle?)
• Hard to understand
• Difficult — intricate
• Where Diddy Men live, saving remains perplexing