Related Clues:

• Try to loosen
• Many a fine artwork
• Petroleum
• Certain paintings
• Chef's bottleful
• Alberta export
• Newfoundland export
• Well output
• Quaker State, e.g.
• Gusher's gush
• Olive __
• It can follow the first word of 17-, 26-, 37-, 50- and 60-Across
• Kuwait export
• Alberta Gold
• Driller's quest, often