The most common and most likely answer to this crossword clue is the 5 letter word MOURN
I've seen this crossword clue in The Guardian
M
O
U
R
N
More clues leading to the result MOURN
- Be sad for us in midst of glumness
- Regret monarch's being besieged by heads of Merchant Navy
- Early in the day for poet, say, to lament?
- What bereaved do with second container for ashes
- Medical Officer on vessel gets to wear black, perhaps
- Keen on rum being drunk
- Lament some from our neighbourhood
- “I quit!” – football manager loses his head over miss
- Wear black uniform during early hours
- Keen runner has easy run
Buddy explains!

The straight part
We know that "miss" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case miss = mourn.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 MOURN mean?
MOURN noun- Sorrow, grief.
- A ring fitted upon the head of a lance to prevent wounding an adversary in tilting.
- To express sadness or sorrow for; to grieve over (especially a death).
- To utter in a sorrowful manner.
- To wear mourning.