The most common and most likely answer to this crossword clue is the 6 letter word TRAGIC
I've seen this crossword clue in The Times
T
R
A
G
I
C
More clues leading to the result TRAGIC
- Calamitous stunt mostly taking in a guide leader
- Soldier in wagon turned up suffering great distress
- Sad when kid in it turned up cold
- Very sad time with smoke going up
- Very unfortunate time, with export from Cuba brought back
- Disastrous as many a dramatic production
- Like Hamlet cigar, ultimately burnt up
- Mock? In a second almost comes to like Greek drama
- . Sad tidings to start with: Corona, possibly, has returned
- Very sad soldier in vehicle going back uphill
Buddy explains!

The straight part
We know that "Sad" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sad = tragic.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 TRAGIC mean?
TRAGIC noun- An obsessive fan, a superfan
- A writer of tragedy.
- A tragedy; a tragic drama.
- Causing great sadness or suffering.
- Relating to tragedy in a literary work.
- (in tabloid newspapers) Having been the victim of a tragedy.