Possible Clues:

• Prison term that is finding one under par
• Golfer's sub-par performance
• Good score for child’s term for flier
• Three strokes on a par-4 hole, e.g
• Badminton projectile
• See 68-Across
• Albatross? Eagle? Yes and no!
• Course coup
• One under empty bar drinking single to pass out
• Bear in mind Mann left, of course, the one under par