The most common and most likely answer to this crossword clue is the 6 letter word THORNY
I've seen this crossword clue in The Sunday Telegraph
T
H
O
R
N
Y
More clues leading to the result THORNY
- Awkward love with sailors in your embrace
- Prickly Scandinavian hero content to leave Norway
- Prickly bush’s last cutting lacerated youth leader
- First of twins desperate for the other to be troublesome
- Tricky warning device in tricky case
- Tricky time getting randy
- Difficult temperature, hot
- Difficult defendant finally up for it
- Difficult Norse god nearly dispensing with earl
- Relocating North Yemen’s capital is causing problems
Buddy explains!

The straight part
We know that "Difficult" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case difficult = thorny.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 THORNY mean?
THORNY adjective- Having thorns or spines
- Troublesome or vexatious
- Aloof and irritable