Related Clues:

• Have/has a duty (to do)
• to (should)
• Is advised
• Should duck?
• Should prove uncommonly tough
• Should an expression of disgust be found in holy books?
• Tough (anag.)
• Crestfallen criminal would be obliged
• Has a duty (to)
• Ought to (do)
• Tough (anag)
• Anything at all should!
• Should get tough when beaten
• Need (to)
• "You ___ to know!"