The most common and most likely answer to this crossword clue is the 3 letter word ILL
I've seen this crossword clue in The Daily Telegraph
I
L
L
More clues leading to the result ILL
- Bad practice to ignore the doctor
- Unwell still, though losing stone
- I shall start off cleansing leg with florid rash
- Trouble the setter is going to!
- Poorly after swallowing tablet, David’s developed rash
- Telling off about set of books stolen from library, say?
- Avril Lavigne’s secret pain
- Sick leave denied wife
- The writer is going to some trouble.
- Badly want to lose weight
Buddy explains!

The straight part
We know that "unfortunate" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case unfortunate = ill.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 ILL mean?
ILL noun- (often pluralized) Trouble; distress; misfortune; adversity.
- Harm or injury.
- Evil; moral wrongfulness.
- A physical ailment; an illness.
- PCP, phencyclidine.
- Evil; wicked (of people).
- Morally reprehensible (of behaviour etc.); blameworthy.
- Indicative of unkind or malevolent intentions; harsh, cruel.
- Unpropitious, unkind, faulty, not up to reasonable standard.
- Unwell in terms of health or physical condition; sick.
- Having an urge to vomit.
- (hip-hop slang) Sublime, with the connotation of being so in a singularly creative way.
- Extremely bad (bad enough to make one ill). Generally used indirectly with to be.
- Unwise; not a good idea.
- Not well; imperfectly, badly; hardly.