The most common and most likely answer to this crossword clue is the 8 letter word SWOTTING
I've seen this crossword clue in The Guardian
S
W
O
T
T
I
N
G
Buddy explains!
The straight part
We know that "learning the hard way" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case learning the hard way = swotting.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.
What does SWOTTING mean?
SWOTTING verb- To study with effort or determination (object of study indicated by "up on").