The most common and most likely answer to this crossword clue is the 8 letter word STINKERS
I've seen this crossword clue in The Guardian
S
T
I
N
K
E
R
S
Buddy explains!
The straight part
We know that "big problems" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case big problems = stinkers.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 STINKERS mean?
STINKERS noun- A person who stinks.
- A contemptible person.
- Something difficult (e.g. a given puzzle) or unpleasant (e.g. negative review, nasty letter).
- Something of poor quality.
- Any of several species of large Antarctic petrels which feed on blubber and carrion and have an offensive odour, such as the giant fulmar.
- A chemist.
- A hot day.