The most common and most likely answer to this crossword clue is the 8 letter word EXACTING
I've seen this crossword clue in The Daily Telegraph
E
X
A
C
T
I
N
G
More clues leading to the result EXACTING
- Challenging former deputy
- Very demanding former partner playing a role
- Tough no longer playing
- Demanding much – no longer acting
- Late performance making undue demands
- Tough old deputy
- Former luvvie’s job in sort of firm that’s hard to please
- Challenging dramatic performance by divorcee
- Demanding old partner putting on a performance
- Performing with former partner is difficult
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 = exacting.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 EXACTING mean?
EXACTING verb- To demand and enforce the payment or performance of, sometimes in a forcible or imperious way.
- To make desirable or necessary.
- To inflict; to forcibly obtain or produce.
- Making excessive demands; difficult to satisfy.
- (of an action, task, etc) Requiring precise accuracy, great care, effort, or attention.
- (of a person or organization) Characterized by exaction.