Crossword puzzle clue "hole in one's knowledge"

Hole in one's knowledge

Hole in one on a par 5 hole

Hole whose eagle would be a hole-in-one

Site of an undesirable hole inside a desirable hole

Duffer's sad 18th-hole reply to "Bogey for you?" ... and 19th-hole request to the bartender?

One-on-one knowledge recipient

Offer one's knowledge

Have ___ in one's knowledge