The most common and most likely answer to this crossword clue is the 8 letter word IDEALIST
I've seen this crossword clue in The Guardian
I
D
E
A
L
I
S
T
More clues leading to the result IDEALIST
- Romantic sort of ladies sex appeal enthrals
- Romantic thought is introduced to lieutenant
- One understanding one’s time as a dreamer
- Romantic English celebs pursue papers
- Visionary that is inspiring a famous boxer
- One seeking perfection? One limited by silly details
- Visionary site laid out
- Visionary fish celebrities
- … clue? Heard composer’s a visionary
- Dreamer I trade with first
Buddy explains!

The straight part
We know that "Dreamer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dreamer = idealist.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 IDEALIST mean?
IDEALIST noun- One who adheres to idealism.
- Someone whose conduct stems from idealism rather than from practicality.
- An unrealistic or impractical visionary.