Possible Clues:

• Mythical knot that's difficult to untie
• Solve problem forcefully - cut the . . . . . . . knot
• ___ knot (difficult problem)
• Legendary knot cut to solve problem
• Knot only loosed by Alexander the Great with a sword
• 'Extremely intricate, as the knot (7)'
• not cut by Greek one we're told
• Alexander cut it, the ___ Knot
• Cut the — knot
• Work managed to keep detective involved