The most common and most likely answer to this crossword clue is the 9 letter word MIDSUMMER
I've seen this crossword clue in The Guardian
M
I
D
S
U
M
M
E
R
More clues leading to the result MIDSUMMER
- I had son interrupting old actor when Bottom played Pyramus
- Return of stupid arithmetician, say, in warm period
- Dreamtime in which folk actor hugs former Tory leader
- Identity’s concealed by masked performer today
- Tory politician cornered by silent performer in heated period
- Location of two maidens in solstice?
- Old actor steals papers revealing the timing of a Shakespeare play
- Unclear about total by sea in France in June?
- A night's dream that's playful?
Buddy explains!

The straight part
We know that "Dreamtime" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dreamtime = midsummer.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 MIDSUMMER mean?
MIDSUMMER noun- The period around the summer solstice; about 21st June in the northern hemisphere.
- The first day of summer
- The middle of summer.
- Midsummer Day, the English quarter day.
- A pagan holiday or Wiccan Sabbat
- Happening in the middle of summer.