Related Clues:

• Unpredictable
• Difficult
• Sly
• Guileful
• Devious
• Awkward
• Deceptive
• Word spelled phonetically by the starts of 1-, 20-, 27-, 36-, 49- and 56-Across
• Complicated
• Problematic
• Tough to figure out
• Crafty, foxy, slippery
• Crafty or difficult
• Crafty, cunning
• Awkward tart's customer needing 'a little yogurt'