The most common and most likely answer to this crossword clue is the 4 plus 3 plus 6 letter word BITE THE BULLET
I've seen this crossword clue in The Guardian
B
I
T
E
T
H
E
B
U
L
L
E
T
More clues leading to the result BITE THE BULLET
Buddy explains!
The straight part
We know that "Face up to unpleasant situation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case face up to unpleasant situation = bite the bullet.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.