Possible Clues:

• Pursued an academic specialty (with ''in'')
• Specialised in a particular subject
• Officer's English degree is specialised for an American
• Specialized (in), in college
• Pursued academically (with "in")
• Judge that prepared or made cases and specialized
• Studied primarily, with 'in'
• Barbara Spenser briefly specialised
• Made one's main study
• Specialized (in)