The most common and most likely answer to this crossword clue is the 5 letter word STIFF
I've seen this crossword clue in Financial Times
S
T
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F
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More clues leading to the result STIFF
Buddy explains!

The straight part
We know that "Difficult/body" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case difficult/body = stiff.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 STIFF mean?
STIFF noun- An average person, usually male, of no particular distinction, skill, or education, often a working stiff or lucky stiff.
- A person who is deceived, as a mark or pigeon in a swindle.
- A cadaver; a dead person.
- A flop; a commercial failure.
- A person who leaves (especially a restaurant) without paying the bill.
- (by extension) A customer who does not leave a tip.
- Any hard hand where it is possible to exceed 21 by drawing an additional card.
- Negotiable instruments, possibly forged.
- To fail to pay that which one owes (implicitly or explicitly) to another, especially by departing hastily.
- To cheat someone
- To tip ungenerously
- (of an object) Rigid; hard to bend; inflexible.
- (of policies and rules and their application and enforcement) Inflexible; rigid.
- (of a person) Formal in behavior; unrelaxed.
- Harsh, severe.
- (of muscles or parts of the body) Painful as a result of excessive or unaccustomed exercise.
- Potent.
- Dead, deceased.
- (of a penis) Erect.
- (of whipping cream or egg whites) Beaten until so aerated that they stand up straight on their own.
- Of an equation: for which certain numerical solving methods are numerically unstable, unless the step size is taken to be extremely small.
- Keeping upright.