The most common and most likely answer to this crossword clue is the 3 plus 6 plus 3 letter word EAT HUMBLE PIE
I've seen this crossword clue in The Daily Telegraph
E
A
T
H
U
M
B
L
E
P
I
E
More clues leading to the result EAT HUMBLE PIE
Buddy explains!
The straight part
We know that "To take a course like this is humiliating" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case to take a course like this is humiliating = eat humble pie.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.