Possible Clues:

• Like 4 and 11, or 24 down and 22 down, or 13 across, 14 and 27
• College student's field of study
• Half of street cut off by obstruction, turning serious
• Chief officer, accountant to leave island
• Consecrate; thank
• The officer is not so sound as a miner
• Highly significant
• Chief - officer
• Significant, main
• Special subject for American officer