Related Clues:

• Fifth wheel
• Outcast
• Loner
• Elimination method
• Oddball
• Nonconformist
• Social dud
• Weirdo
• Misfit
• Square peg in a round hole, say
• Social outcast
• Conspicuous one
• Fish out of water
• Maladjusted person
• Square peg, e.g.